Publications in 2010
Discovery of VHE gamma-rays from the BL Lac object PKS 0548-322
H. E. S. S. collaboration : F. Aharonian, Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Benbow, W., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Chounet, L. -., Clapson, A. C., Coignet, G., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füssling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hauser, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzyński, K., Katz, U., Kaufmann, S., Kendziorra, E., Kerschhagg, M., Khangulyan, D., Khélifi, B., Keogh, D., Kluźniak, W., Kneiske, T., Komin, N., Kosack, K., Lamanna, G., Lenain, J. -., Lohse, T., Marandon, V., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J., de Oña Wilhelm, E., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P. -., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Renaud, M., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sikora, M., Skilton, J. L., Sol, H., Spangler, D., Stawarz, L., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Szostek, A., Tam, P. H., Tavernet, J. -., Terrier, R., Tibolla, O., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volp, F., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2010 , eprint arXiv:1006.5289
Abstract:
PKS 0548-322 (z=0.069) is a ``high-frequency-peaked'' BL Lac object and a candidate very high energy (VHE, E>100 GeV) gamma-ray emitter, due to its high X-ray and radio flux. Observations at the VHE band provide insights into the origin of very energetic particles present in this source and the radiation processes at work. We report observations made between October 2004 and January 2008 with the H.E.S.S. array, a four imaging atmospheric-Cherenkov telescopes. Contemporaneous UV and X-ray observations with the Swift satellite in November 2006 are also reported. PKS 0548-322 is detected for the first time in the VHE band with H.E.S.S. We measure an excess of 216 gamma-rays corresponding to a significance of 5.6 standard deviations. The photon spectrum of the source is described by a power-law, with a photon index of Gamma=2.86 +/- 0.34 (stat) +/- 0.10 (sys). The integral flux above 200 GeV is 1.3 % of the flux of the Crab Nebula, and is consistent with being constant in time. Contemporaneous Swift/XRT observations reveal an X-ray flux between 2 and 10 keV of F_{2-10 keV}=2.3 +/- 0.2 x 10^{-11} erg.cm^{-2}. s^{-1}, an intermediate intensity state with respect to previous observations. The spectral energy distribution can be reproduced using a simple one-zone synchrotron self Compton model, with parameters similar those observed for other sources of this type.
Absolute properties of the main-sequence eclipsing binary FM Leo
Ratajczak, M., Kwiatkowski, T., Schwarzenberg-Czerny, A., Dimitrov, W., Konacki, M., Hełminiak, K. G., Bartczak, P., Fagas, M., Kamiński, K., Kankiewicz, P., Borczyk, W., and Rożek, A.
2010 , Monthly Notices of the Royal Astronomical Society, Volume 402, Issue 4, pp. 2424-2428.
Abstract:
First spectroscopic and new photometric observations of the eclipsing binary FM Leo are presented. The main aims were to determine the orbital and stellar parameters of the two components and their evolutionary stage. First spectroscopic observations of the system were obtained with the David Dunlap Observatory and Poznań Spectroscopic Telescope spectrographs. The results of the orbital solution from radial velocity curves are combined with those derived from the light-curve analysis (V-band photometry from the All Sky Automated Survey and supplementary observations of eclipses with the 1 and 0.35m telescopes) to derive orbital and stellar parameters. JKTEBOP, Wilson-Devinney binary modelling codes and a two-dimensional cross-correlation method were applied for the analysis. We find the masses to be M1 = 1.318 +/- 0.007 and M2 = 1.287 +/- 0.007Msolar and the radii to be R1 = 1.648 +/- 0.043 and R2 = 1.511 +/- 0.049 Rsolar for primary and secondary stars, respectively. The evolutionary stage of the system is briefly discussed by comparing physical parameters with current stellar evolution models. We find that the components are located at the main sequence, with an age of about 3Gyr.
Abundances in planetary nebulae (Chiappini+, 2009)
Chiappini, C., Górny, S. K., Stasinska, G., and Barbuy, B.
2010 , VizieR On-line Data Catalog: J/A+A/494/591. Originally published in: 2009A&A...494..591C
Abstract:
We present new plasma diagnostics and abundances of a sample of planetary nebulae located in the Galactic bulge (168 objects), the Galactic inner disk (61 objects) and in the LMC (110 objects).
(6 data files).
Abundances in planetary nebulae (Gorny+, 2009)
Górny, S. K., Chiappini, C., Stasinska, G., and Cuisinier, F.
2010 , VizieR On-line Data Catalog: J/A+A/500/1089. Originally published in: 2009A&A...500.1089G
Abstract:
We present new spectroscopic data (90 objects) and derived plasma diagnostics and abundances of a sample of planetary nebulae in the direction of the Galactic center. The spectra were obtained in 2001/2002 with the 4-m class telescope at the Cerro Tololo Interamerican Observatory and the European Southern Observatory.
(4 data files).
Detecting Circumbinary Planets Using Eclipse Timing of Binary Stars - From Simulations to Observations
Sybilski, P., Konacki, M., and Kozlowski, S.
2010 , American Astronomical Society, AAS Meeting #216, #425.03
Abstract:
The Light-Time Effect (LTE) occurs whenever the distance between the observer and any kind of periodic signal occurring in space changes. The usual cause of this is the reflex motion about the system's barycenter due
to the gravitational influence of one or more additional bodies. With a sufficient precision of the times of eclipses, the eclipse timing can be used to detect substellar or even planetary mass companions.
The main goal of the poster is to investigate the potential of the photometry based eclipse timing of binary stars as a method of detecting circumbinary planets. In the models we assume that the companion orbits a binary star
in a circular Keplerian orbit. We analyze throug the numerical simulations both the space and ground based photometry cases. In particular, we study the usefulness of the on-going COROT and Kepler missions in detecting circumbinary planets.
We determine the sensitivity of the eclipse timing technique to circumbinary planets for the ground and space based photometric observations. We provide suggestions for the best targets, observing strategies and instruments for the eclipse timing method. Finally, we present some preliminary results comparing simulations and real observations.
Detecting circumbinary planets using eclipse timing of binary stars - numerical simulations
Sybilski, P., Konacki, M., and Kozłowski, S.
2010 , Monthly Notices of the Royal Astronomical Society, Volume 405, Issue 1, pp. 657-665.
Abstract:
The presence of a body in an orbit around a close eclipsing binary star manifests itself through the light time effect influencing the observed times of eclipses as both the close binary and the circumbinary companions move around the common centre of mass. This fact combined with the periodicity with which the eclipses occur can be used to detect the companions. Given a sufficient precision of the times of eclipses, the eclipse timing can be employed to detect substellar or even planetary mass companions.
The main goal of this paper is to investigate the potential of the photometry-based eclipse timing of binary stars as a method of detecting circumbinary planets. In the models we assume that the companion orbits a binary star in a circular Keplerian orbit. We analyse both the space- and ground-based photometry cases. In particular, we study the usefulness of the ongoing CoRoT and Kepler missions in detecting circumbinary planets. We also explore the relations binding the planet discovery space with the physical parameters of the binaries and the geometrical parameters of their light curves. We carry out detailed numerical simulations of the eclipse timing by employing a relatively realistic model of the light curves of eclipsing binary stars. We study the influence of the white and red photometric noises on the timing precision. We determine the sensitivity of the eclipse timing technique to circumbinary planets for the ground- and space-based photometric observations. We provide suggestions for the best targets, observing strategies and instruments for the eclipse timing method. Finally, we compare the eclipse timing as a planet detection method with the radial velocities and astrometry.
Discovery of 21 Micron Sources in the Magellanic Clouds
Volk, K., Matsuura, M., Bernard-Salas, J., Sloan, G. C., Szczerba, R., Kemper, F., Woods, P. M., Hrivnak, B. J., Tielens, X., Meixner, M., Gordon, K., Indebetouw, R., van Loon, J., and Marengo, M.
2010 , American Astronomical Society, AAS Meeting #215, #459.07; Bulletin of the American Astronomical Society, Vol. 42, p.486
Abstract:
We report the detection of the unidentified emission feature at 21 microns in infrared spectra of eight post-AGB objects in the Magellanic Clouds. This is the first detection of the feature in extragalactic objects. The observations were made by the IRS instrument on the Spitzer Space Telescope, as part of multiple observing programs. The eight new detections are considerable, given that only 15 post-AGB objects in the Galaxy have been identified with 21-micron features. The infrared spectra with 21-micron features in the Magellanic Clouds tend to show stronger emission from the accompanying aromatic hydrocarbon (PAH) features than those in the Galaxy do. The dust in the new objects also generally appears to be hotter, which might imply that they have not evolved as far from the AGB as their Galactic analogues. The 21-micron features are weaker on average than in the Galactic objects, although two of the objects do show strong features. We present the Spitzer spectra of these objects as well as the available ground-based optical and near-infrared photometry and some preliminary results from radiative transfer models.
Excitation of the molecular gas in the nuclear region of M82
Loenen, A. F., van der Werf, P. P., Güsten, R., Meijerink, R., Israel, F. P, Requena-Torres, M. A., García-Burillo, S., Harris, A. I., Klein, T., Kramer, C., Lord, S., Martín-Pintado, J., Röllig, M., Stutzki, J., Szczerba, R., Weiß, A., Philipp-May, S., Yorke, H., Caux, E., Delforge, B., Helmich, F., Lorenzani, A., Morris, P., Philips, T. G., Risacher, C., and Tielens, A. G. G. M.
2010 , eprint arXiv:1006.5006
Abstract:
We present high resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M82. Six 12CO lines, 2 13CO lines and 4 fine-structure lines are detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n=10^3.5 cm^-3) clouds, with column densities of N_H=10^21.5 cm^-2 and a relatively low UV radiation field (GO = 10^2). The remaining gas is predominantly found in clouds with higher densities (n=10^5 cm^-3) and radiation fields (GO = 10^2.75), but somewhat lower column densities (N_H=10^21.2 cm^-2). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n=10^6 cm^-3) and UV field (GO = 10^3.25). These results show the strength of multi-component modeling for the interpretation of the integrated properties of galaxies.
First detection of VHE γ-rays from SN 1006 by HESS
Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Beilicke, M., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L.-M., Clapson, A. C., Coignet, G., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füßling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hauser, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzyński, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Klochkov, D., Kluźniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lemoine-Goumard, M., Lenain, J.-P., Lohse, T., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J.-F., de Oña Wilhelmi, E., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., de Los Reyes, R., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schönwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sushch, I., Sikora, M., Skilton, J. L., Sol, H., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Szostek, A., Tam, P. H., Tavernet, J.-P., Terrier, R., Tibolla, O., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Vincent, P., Vink, J., Vivier, M., Völk, H. J., Volpe, F., Vorobiov, S., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2010 , Astronomy and Astrophysics, Volume 516, id.A62
Abstract:


Aims. Recent theoretical predictions of the lowest very high energy (VHE) luminosity of SN 1006 are only a factor 5 below the previously published HESS upper limit, thus motivating further in-depth observations of this source.

Methods. Deep observations at VHE energies (above 100 GeV) were carried out with the high energy stereoscopic system (HESS) of Cherenkov Telescopes from 2003 to 2008. More than 100 h of data have been collected and subjected to an improved analysis procedure.

Results. Observations resulted in the detection of VHE γ-rays from SN 1006. The measured γ-ray spectrum is compatible with a power-law, the flux is of the order of 1% of that detected from the Crab Nebula, and is thus consistent with the previously established HESS upper limit. The source exhibits a bipolar morphology, which is strongly correlated with non-thermal X-rays.

Conclusions. Because the thickness of the VHE-shell is compatible with emission from a thin rim, particle acceleration in shock waves is likely to be the origin of the γ-ray signal. The measured flux level can be accounted for by inverse Compton emission, but a mixed scenario that includes leptonic and hadronic components and takes into account the ambient matter density inferred from observations also leads to a satisfactory description of the multi-wavelength spectrum.
First detection of VHE gamma-rays from SN 1006 by H.E.S.S
HESS Collaboration, Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Beilicke, M., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L. -., Clapson, A. C., Coignet, G., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füßling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hauser, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzy'nski, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Klochkov, D., Klu'zniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lemoine-Goumard, M., Lenain, J. -., Lohse, T., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Méhault, J., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J., Orford, E. d. O. W. K. J., Ostrowski, M., Panter, M., Pedaletti, M. P. A. G., Pelletier, G., Petrucci, P. -., Pita, S., Pühlhofer, 1. G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., de los Reyes, R., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schönwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sushch, I., Sikora, M., Skilton, J. L., Sol, H., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Szostek, A., Tam, P. H., Tavernet, J. -., Terrier, R., Tibolla, O., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Vincent, P., Vink, J., Vivier, M., Völk, H. J., Volpe, F., Vorobiov, S., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2010 , eprint arXiv:1004.2124
Abstract:
Recent theoretical predictions of the lowest very high energy (VHE) luminosity of SN 1006 are only a factor 5 below the previously published H.E.S.S. upper limit, thus motivating further in-depth observations of this source. Deep observations at VHE energies (above 100 GeV) were carried out with the High Energy Stereoscopic System (H.E.S.S.) of Cherenkov Telescopes from 2003 to 2008. More than 100 hours of data have been collected and subjected to an improved analysis procedure. Observations resulted in the detection of VHE gamma-rays from SN 1006. The measured gamma-ray spectrum is compatible with a power-law, the flux is of the order of 1% of that detected from the Crab Nebula, and is thus consistent with the previously established H.E.S.S. upper limit. The source exhibits a bipolar morphology, which is strongly correlated with non-thermal X-rays. Because the thickness of the VHE-shell is compatible with emission from a thin rim, particle acceleration in shock waves is likely to be the origin of the gamma-ray signal. The measured flux level can be accounted for by inverse Compton emission, but a mixed scenario that includes leptonic and hadronic components and takes into account the ambient matter density inferred from observations also leads to a satisfactory description of the multi-wavelength spectrum.
HST/WFPC2 observations of the LMC pulsar PSR B0540-69
Mignani, R. P., Sartori, A., de Luca, A., Rudak, B., Słowikowska, A., Kanbach, G., and Caraveo, P. A.
2010 , Astronomy and Astrophysics, Volume 515, id.A110
Abstract:

Context. The study of the younger, and brighter, pulsars is important for understanding the optical emission properties of isolated neutron stars through observations which, even in the 10 m-class telescope era, are much more challenging for older and fainter objects. PSR B0540-69, the second brightest (V~22) optical pulsar, is obviously a primary target for these investigations.

Aims. The aims of this work are several: (i) constraining the pulsar proper motion and its velocity on the plane of the sky and improving the determination of the pulsar coordinates through optical astrometry; (ii) obtaining a more precise characterisation of the pulsar optical spectral energy distribution (SED) through a consistent set of multi-band, high-resolution, imaging photometry observations and studying the relation with the X-ray spectrum, including the presence of a spectral turnover between the two bands. Last, we aim at (iii) measuring the pulsar optical phase-averaged linear polarisation, for which only a preliminary and uncertain measurement has been obtained so far from ground-based observations, and at testing the predictions of different neutron star magnetosphere models.

Methods. We performed high-resolution observations of PSR B0540-69 with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST), in both direct imaging and polarimetry modes.

Results. From multi-epoch astrometry we set a 3 σ upper limit of 1 mas yr-1 on the pulsar proper motion, implying a transverse velocity <250 km s-1 at the 50 kpc LMC distance. Moreover, we determined the pulsar absolute position with an unprecedented accuracy of 70 mas. From multi-band photometry we characterised the pulsar power-law spectrum and derived the most accurate measurement of the spectral index (α_O = 0.70 ± 0.07), which indicates a spectral turnover between the optical and X-ray bands. Finally, from polarimetry we obtained a new measurement of the pulsar phase-averaged polarisation degree (PD = 16% ± 4%), consistent with magnetosphere models, depending on the actual intrinsic polarisation degree and depolarisation factor, and we found that the polarisation vector (22° ± 12° position angle) is possibly aligned with the semi-major axis of the pulsar-wind nebula and with the apparent proper motion direction of its bright emission knot.

Conclusions. Deeper studies with the HST can only be possible with the refurbished Advanced Camera for Surveys (ACS) and with the new Wide Field Camera 3 (WFC3).
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc. under contract No. NAS 5-26555.
Localizing the VHE γ-ray source at the Galactic Centre
Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Braun, I., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L.-M., Clapson, A. C., Coignet, G., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füßling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzyński, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Klochkov, D., Kluźniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lenain, J.-P., Lohse, T., Marandon, V., Martineau-Huynh, O., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J.-F., de Oña Wilhelmi, E., Orford, K. J., Ostrowski, M., Panter, M., Arribas, M. P., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schönwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sikora, M., Skilton, J. L., Sol, H., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Sushch, I., Szostek, A., Tam, P. H., Tavernet, J.-P., Terrier, R., Tibolla, O., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2010 , Monthly Notices of the Royal Astronomical Society, Volume 402, Issue 3, pp. 1877-1882.
Abstract:
The inner 10pc of our Galaxy contains many counterpart candidates of the very high energy (VHE; >100GeV) γ-ray point source HESS J1745-290. Within the point spread function of the H.E.S.S. measurement, at least three objects are capable of accelerating particles to VHE and beyond and of providing the observed γ-ray flux. Previous attempts to address this source confusion were hampered by the fact that the projected distances between these objects were of the order of the error circle radius of the emission centroid (34arcsec, dominated by the pointing uncertainty of the H.E.S.S. instrument). Here we present H.E.S.S. data of the Galactic Centre region, recorded with an improved control of the instrument pointing compared to H.E.S.S. standard pointing procedures. Stars observed during γ-ray observations by optical guiding cameras mounted on each H.E.S.S. telescope are used for off-line pointing calibration, thereby decreasing the systematic pointing uncertainties from 20 to 6arcsec per axis. The position of HESS J1745-290 is obtained by fitting a multi-Gaussian profile to the background-subtracted γ-ray count map. A spatial comparison of the best-fitting position of HESS J1745-290 with the position and morphology of candidate counterparts is performed. The position is, within a total error circle radius of 13arcsec, coincident with the position of the supermassive black hole Sgr A* and the recently discovered pulsar wind nebula candidate G359.95-0.04. It is significantly displaced from the centroid of the supernova remnant Sgr A East, excluding this object with high probability as the dominant source of the VHE γ-ray emission.
Multi-wavelength Observations of H 2356-309
HESS Collaboration, Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Benbow, W., Bernloehr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Buehler, R., Bulik, T., Buesching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L. -., Clapson, A. C., Coignet, G., Costamante, L., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Atai, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fiasson, A., Foerster, A., Fontaine, G., Fuessling, M., Gabici, S., Gallant, Y. A., Gerard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glueck, B., Goret, P., Goering, D., Hampf, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzynski, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khelifi, B., Keogh, D., Klochkov, D., Kluzniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lenain, J. -., Lohse, T., Lu, C. -., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Mehault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nguyen, N., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J., de Ona Wilhelmi, E., Opitz, B., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P. -., Pita, S., Puehlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., de los Reyes, R., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schoeck, F. M., Schoenwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sushch, I., Sikora, M., Skilton, J. L., Sol, H., Stawarz, L., Steenkamp, R., Stegmann, C., Stinzing, F., Szostek, A., Tam, P. H., Tavernet, J. -., Terrier, R., Tibolla, O., Tluczykont, M., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Viana, A., Vincent, P., Vivier, M., Voelk, H. J., Volpe, F., Vorobiov, S., Wagner, S. J., Ward, M., Zdziarski, A. A., Zech, A., and Zechlin, H. -.
2010 , eprint arXiv:1004.2089
Abstract:
AIMS: The properties of the broad-band emission from the high-frequency peaked BL Lac H 2356-309 (z=0.165) are investigated. METHODS: Very High Energy (VHE; E > 100 GeV) observations of H 2356-309 were performed with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Simultaneous optical/UV and X-ray observations were made with the XMM-Newton satellite on June 12/13 and June 14/15, 2005. NRT radio observations were also contemporaneously performed in 2005. ATOM optical monitoring observations were also made in 2007. RESULTS: A strong VHE signal, ~13 sigma total, was detected by HESS after the four years HESS observations (116.8 hrs live time). The integral flux above 240 GeV is I(>240 GeV) = (3.06 +- 0.26 {stat} +- 0.61 {syst}) x 10^{-12} cm^{-2} s^{-1}, corresponding to ~1.6% of the flux observed from the Crab Nebula. A time-averaged energy spectrum is measured from 200 GeV to 2 TeV and is characterized by a power law (photon index of Gamma = 3.06 +- 0.15 {stat} +- 0.10 {syst}). Significant small-amplitude variations in the VHE flux from H 2356-309 are seen on time scales of months and years, but not on shorter time scales. No evidence for any variations in the VHE spectral slope are found within these data. The XMM-Newton X-ray measurements show a historically low X-ray state, characterized by a hard, broken-power-law spectrum on both nights. CONCLUSIONS: The broad-band spectral energy distribution (SED) of the blazar can be adequately fit using a simple one-zone synchrotron self-Compton (SSC) model. In the SSC scenario, higher VHE fluxes could be expected in the future since the observed X-ray flux is at a historically low level.
Multi-wavelength observations of H 2356-309
Hess Collaboration, Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Benbow, W., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L.-M., Clapson, A. C., Coignet, G., Costamante, L., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fiasson, A., Förster, A., Fontaine, G., Füßling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hampf, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzyński, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Klochkov, D., Klužniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lenain, J.-P., Lohse, T., Lu, C.-C., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nguyen, N., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J.-F., de Oña Wilhelmi, E., Opitz, B., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., de Los Reyes, R., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schönwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sushch, I., Sikora, M., Skilton, J. L., Sol, H., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Szostek, A., Tam, P. H., Tavernet, J.-P., Terrier, R., Tibolla, O., Tluczykont, M., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Viana, A., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Vorobiov, S., Wagner, S. J., Ward, M., Zdziarski, A. A., Zech, A., and Zechlin, H.-S.
2010 , Astronomy and Astrophysics, Volume 516, id.A56
Abstract:


Aims. The properties of the broad-band emission from the high-frequency peaked BL Lac H 2356-309 (z = 0.165) are investigated.

Methods. Very high energy (VHE; E > 100 GeV) observations of H 2356-309 were performed with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Simultaneous optical/UV and X-ray observations were made with the XMM-Newton satellite on June 12/13 and June 14/15, 2005. NRT radio observations were also contemporaneously performed in 2005. ATOM optical monitoring observations were also made in 2007.

Results. A strong VHE signal, ~13σ total, was detected by HESS after the four years HESS observations (116.8 h live time). The integral flux above 240 GeV is I(>240 GeV) = (3.06 ± 0.26stat ± 0.61syst) × 10-12 cm-2 s-1, corresponding to ~1.6% of the flux observed from the Crab Nebula. A time-averaged energy spectrum is measured from 200 GeV to 2 TeV and is characterized by a power law (photon index of Γ = 3.06 ± 0.15stat ± 0.10syst). Significant small-amplitude variations in the VHE flux from H 2356-309 are seen on time scales of months and years, but not on shorter time scales. No evidence for any variations in the VHE spectral slope are found within these data. The XMM-Newton X-ray measurements show a historically low X-ray state, characterized by a hard, broken-power-law spectrum on both nights.

Conclusions. The broad-band spectral energy distribution (SED) of the blazar can be adequately fit using a simple one-zone synchrotron self-Compton (SSC) model. In the SSC scenario, higher VHE fluxes could be expected in the future since the observed X-ray flux is at a historically low level.
New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge
Górny, S. K., Perea-Calderón, J. V., García-Hernández, D. A., García-Lario, P., and Szczerba, R.
2010 , Astronomy and Astrophysics, Volume 516, id.A39
Abstract:


Aims. We investigate Galactic bulge planetary nebulae without emission-line central stars for which peculiar infrared spectra have been obtained with the Spitzer Space Telescope, including the simultaneous signs of oxygen and carbon based dust. Three separate sub-groups can be defined characterized by the different chemical composition of the dust and the presence of crystalline and amorphous silicates.

Methods. We use literature data to analyze the different nebular properties and deduce both the evolutionary status and the origin of these three groups. In particular, we check whether there are signs of evolutionary links between dual-dust chemistry planetary nebulae without detected emission-line central stars and those with emission-line stars.

Results. Our primary finding is that the classification based on the dust properties is reflected in the more general properties of these planetary nebulae. However, some observed properties are difficult to relate to the common view of planetary nebulae. In particular, it is challenging to interpret the peculiar gas chemical composition of many analyzed objects in the standard picture of the evolution of planetary nebulae progenitors. We confirm that the dual-dust chemistry phenomenon is not limited to planetary nebulae with emission-line central stars.

Conclusions. Our results clearly indicate that there is no unique road to the formation of planetary nebulae even in a homogeneous environment such as the Galactic bulge. The evolution of a single asymptotic giant branch star may lead to the formation of different types of planetary nebulae. In addition, the evolution in a close binary system should sometimes also be considered.
Based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.
PKS 2005-489 at VHE: four years of monitoring with HESS and simultaneous multi-wavelength observations
HESS Collaboration, Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Benbow, W., Bernlöhr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Chounet, L.-M., Clapson, A. C., Coignet, G., Costamante, L., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Füßling, M., Gabici, S., Gallant, Y. A., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzyński, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khélifi, B., Keogh, D., Klochkov, D., Kluźniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lenain, J.-P., Lohse, T., Marandon, V., Martineau-Huynh, O., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J.-F., de Oña Wilhelmi, E., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Renaud, M., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sikora, M., Skilton, J. L., Sol, H., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Szostek, A., Tam, P. H., Tavernet, J.-P., Terrier, R., Tibolla, O., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2010 , Astronomy and Astrophysics, Volume 511, id.A52
Abstract:


Aims. Our aim is to study the very high energy (VHE; E>100 GeV) γ-ray emission from BL Lac objects and the evolution in time of their broad-band spectral energy distribution (SED).

Methods. VHE observations of the high-frequency peaked BL Lac object PKS 2005-489 were made with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Three simultaneous multi-wavelength campaigns at lower energies were performed during the HESS data taking, consisting of several individual pointings with the XMM-Newton and RXTE satellites.

Results. A strong VHE signal, ~17σ total, from PKS 2005-489 was detected during the four years of HESS observations (90.3 h live time). The integral flux above the average analysis threshold of 400 GeV is ~3% of the flux observed from the Crab Nebula and varies weakly on time scales from days to years. The average VHE spectrum measured from ~300 GeV to ~5 TeV is characterized by a power law with a photon index, Γ = 3.20± 0.16_stat± 0.10_syst. At X-ray energies the flux is observed to vary by more than an order of magnitude between 2004 and 2005. Strong changes in the X-ray spectrum (ΔΓX ≈ 0.7) are also observed, which appear to be mirrored in the VHE band.

Conclusions. The SED of PKS 2005-489, constructed for the first time with contemporaneous data on both humps, shows significant evolution. The large flux variations in the X-ray band, coupled with weak or no variations in the VHE band and a similar spectral behavior, suggest the emergence of a new, separate, harder emission component in September 2005.
Supported by CAPES Foundation, Ministry of Education of Brazil.Now at Harvard-Smithsonian Center for Astrophysics, Cambridge, USA.Now at W.W. Hansen Experimental Physics Laboratory & Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, USA.
Precise Astrometry of Visual Binaries with Adaptive Optics. A way for finding exoplanets?
Hełminiak, K. and Konacki, M.
2010 , EAS Publications Series, Volume 41, 2010, pp.103-106
Abstract:
We present the results of our study of astrometric stability of 200-in Hale (Mt. Palomar) and 10-m Keck II (Mauna Kea) telescopes, both with Adaptive Optics (AO) facilities. A group of nearby visual binaries and multiples was observed in near infrared, relative separations and position angles measured. We have also checked the influence of some systematic effects (e.g. atmospherical refraction, varying plate scale factor) on result and precision of astrometric measurements. We conclude that in visual binaries astrometrical observations it is possible to achieve much better precision than 1 miliarcsecond [mas], which in many cases allows detection of the astrometrical signal produced by planetary-mass object.
Spectroscopic Survey of Detached Eclipsing Binaries from the ASAS Catalog
Hełminiak, K., Konacki, M., Kaluzny, J., Rozyczka, M., Zloczewski, K., Ratajczak, M., Muterspaugh, M. W., Reichart, D. E., Ivarsen, K. M., Haislip, J. B., Crain, A., Foster, A. C., Nysewander, M. C., and LaCluyze, A. P.
2010 , American Astronomical Society, AAS Meeting #216, #423.03
Abstract:
We present the most interesting results from our survey of eclipsing binaries from the All-Sky Automated Survey (ASAS) catalog. Radial velocities were calculated from high-resolution spectra obtained with Keck I/HIRES, Radcliffe/GIRAFFE and AAT/UCLES telescopes/spectrographs. A novel iodine cell technique for double-lined binaries was also involved. Photometry was taken directly from the ASAS or from dedicated observations at the Elizabeth telescope (SAAO) and fully-automated PROMPT facility.
For a sample of systems we derived very precise absolute values of fundamental parameters. In our sample we found 6 new low-mass systems, 4 pre-main-sequence candidates, and several other binaries interesting from the evolutionary point of view.
The chemical composition of TS 01, the most oxygen-deficient planetary nebula. AGB nucleosynthesis in a metal-poor binary star
Stasińska, G., Morisset, C., Tovmassian, G., Rauch, T., Richer, M. G., Peña, M., Szczerba, R., Decressin, T., Charbonnel, C., Yungelson, L., Napiwotzki, R., Simón-Díaz, S., and Jamet, L.
2010 , Astronomy and Astrophysics, Volume 511, id.A44
Abstract:
The planetary nebula TS 01 (also called PN G 135.9+55.9 or SBS 1150+599A) with its record-holding low oxygen abundance and its double degenerate close binary core (period 3.9 h) is an exceptional object located in the Galactic halo. We have secured observational data in a complete wavelength range to pin down the abundances of half a dozen elements in the nebula. The abundances are obtained via detailed photoionization modelling which takes into account all the observational constraints (including geometry and aperture effects) using the pseudo-3D photoionization code Cloudy_3D. The spectral energy distribution of the ionizing radiation is taken from appropriate model atmospheres. Incidentally we find from the new observational constraints that both stellar components contribute to the ionization: the “cool” one provides the bulk of hydrogen ionization, while the “hot” one is responsible for the presence of the most highly charged ions, which explains why previous attempts to model the nebula experienced difficulties. The nebular abundances of C, N, O, and Ne are found to be 1/3.5, 1/4.2, 1/70, and 1/11 of the solar value respectively, with uncertainties of a factor 2. Thus the extreme O deficiency of this object is confirmed. The abundances of S and Ar are less than 1/30 of solar. The abundance of He relative to H is 0.089 ± 0.009. Standard models of stellar evolution and nucleosynthesis cannot explain the abundance pattern observed in the nebula. To obtain an extreme oxygen deficiency in a star whose progenitor has an initial mass of about 1 M requires an additional mixing process, which can be induced by stellar rotation and/or by the presence of the close companion. We have computed a stellar model with an initial mass of 1 M, appropriate metallicity, and initial rotation of 100 km s-1, and find that rotation greatly improves the agreement between the predicted and observed abundances.
Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.Based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.
The Keck I/HIRES and TNG/Sarg Radial Velocity Survey of Speckle Binary Stars.
Ratajczak, M., Konacki, M., Kulkarni, S. R., and Muterspaugh, M. W.
2010 , American Astronomical Society, AAS Meeting #216, #429.02
Abstract:
A sample of about 150 speckle binary stars was observed with the Keck I telescope and its echelle HIRES spectrograph over the years 2003-2007 in an effort to detect substellar and planetary companions to components of binary and multiple star systems. This data set was supplemented with the data obtained at the TNG telescope equipped with the Sarg echelle spectrograph over the years 2006-2007. The high-resolution (R=65000 for HIRES and R=86000 for Sarg) and high signal to noise(typically 75-150) spectra were used to derive radial velocities of the components of the observed speckle binaries. Here we present a summary of this effort which includes limits to planetary companions, new triple star systems and improved orbital solutions of a few known stellar systems.
The nature of pulsar radio emission
Dyks, J., Rudak, B., and Demorest, P.
2010 , Monthly Notices of the Royal Astronomical Society, Volume 401, Issue 3, pp. 1781-1795.
Abstract:
High-quality averaged radio profiles of some pulsars exhibit double, highly symmetric features both in emission and in absorption. It is shown that both types of feature are produced by a split fan beam of extraordinary-mode curvature radiation that is emitted/absorbed by radially extended streams of magnetospheric plasma. With no emissivity in the plane of the stream, such a beam produces bifurcated emission components (BFCs) when our line of sight passes through the plane. An example of a double component created in this way is present in the averaged profile of the 5-ms pulsar J1012+5307. We show that the component can indeed be very well fitted by the textbook formula for the non-coherent beam of curvature radiation in the polarization state that is orthogonal to the plane of electron trajectory. The observed width of the BFC decreases with increasing frequency at a rate that confirms the curvature origin. Likewise, the double absorption features (double notches) are produced by the same beam of the extraordinary-mode curvature radiation, when it is eclipsed by thin plasma streams. The intrinsic property of curvature radiation to create bifurcated fan beams explains the double features in terms of a very natural geometry and implies the curvature origin of pulsar radio emission. Similarly, the `double conal' profiles of class D result from a cut through a wider stream with finite extent in magnetic azimuth. Therefore, their width reacts very slowly to changes of viewing geometry resulting from geodetic precession. The stream-cut interpretation implies a highly non-orthodox origin of both the famous S-swing of polarization angle and the low-frequency pulse broadening in D profiles. The azimuthal structure of polarization modes in the curvature radiation beam provides an explanation for the polarized `multiple imaging' and the edge depolarization of pulsar profiles.
The Radial Velocity Tatooine Search For Circumbinary Planets
Konacki, M., Muterspaugh, M. W., Kulkarni, S. R., and Hełminiak, K. G.
2010 , American Astronomical Society, AAS Meeting #216, #311.02
Abstract:
We will present the first results from our on-going radial velocity survey for circumbinary planets. The survey is possible thanks to our novel radial velocity technique employing an iodine absorption cell which for the first time allows us to reach single m/s RV precision for double-lined binary stars. Based on the spectra collected with the Keck I/Hires, TNG/Sarg, and Shane/CAT/Hamspec telescopes/spectrographs over the years 2003-2008 we obtained planet detection limits for a sample of double-lined binary stars. For this initial sample of targets, we can rule out planets on dynamically stable orbits with masses as small as 0.3 to 3MJup for the orbital periods of up to 5.3 years.
The SAGE-Spec Spitzer Legacy Program: The Life Cycle of Dust and Gas in the Large Magellanic Cloud
Kemper, F., Woods, P. M., Antoniou, V., Bernard, J.-P., Blum, R. D., Boyer, M. L., Chan, J., Chen, C.-H. R., Cohen, M., Dijkstra, C., Engelbracht, C., Galametz, M., Galliano, F., Gielen, C., Gordon, K. D., Gorjian, V., Harris, J., Hony, S., Hora, J. L., Indebetouw, R., Jones, O., Kawamura, A., Lagadec, E., Lawton, B., Leisenring, J. M., Madden, S. C., Marengo, M., Matsuura, M., McDonald, I., McGuire, C., Meixner, M., Mulia, A. J., O'Halloran, B., Oliveira, J. M., Paladini, R., Paradis, D., Reach, W. T., Rubin, D., Sandstrom, K., Sargent, B. A., Sewilo, M., Shiao, B., Sloan, G. C., Speck, A. K., Srinivasan, S., Szczerba, R., Tielens, A. G. G. M., van Aarle, E., Van Dyk, S. D., van Loon, J. T., Van Winckel, H., Vijh, U. P., Volk, K., Whitney, B. A., Wilkins, A. N., and Zijlstra, A. A.
2010 , The Publications of the Astronomical Society of the Pacific, Volume 122, Issue 892, pp. 683-700.
Abstract:
The SAGE-Spec Spitzer Legacy program is a spectroscopic follow-up to the SAGE-LMC photometric survey of the Large Magellanic Cloud carried out with the Spitzer Space Telescope. We present an overview of SAGE-Spec and some of its first results. The SAGE-Spec program aims to study the life cycle of gas and dust in the Large Magellanic Cloud and to provide information essential to the classification of the point sources observed in the earlier SAGE-LMC photometric survey. We acquired 224.6 h of observations using the infrared spectrograph and the spectral energy distribution (SED) mode of the Multiband Imaging Photometer for Spitzer. The SAGE-Spec data, along with archival Spitzer spectroscopy of objects in the Large Magellanic Cloud, are reduced and delivered to the community. We discuss the observing strategy, the specific data-reduction pipelines applied, and the dissemination of data products to the scientific community. Initial science results include the first detection of an extragalactic 21 μm feature toward an evolved star and elucidation of the nature of disks around RV Tauri stars in the Large Magellanic Cloud. Toward some young stars, ice features are observed in absorption. We also serendipitously observed a background quasar, at a redshift of z ≈ 0.14, which appears to be hostless.
V4332 Sagittarii: A circumstellar disc obscuring the main object
Kamiński, T., Schmidt, M., and Tylenda, R.
2010 , eprint arXiv:1007.0131
Abstract:
V4332 Sgr experienced an outburst in 1994 whose observational characteristics in many respects resemble those of the eruption of V838 Mon in 2002. It has been proposed that these objects erupted due to a stellar-merger event. Our aim is to derive, from observational data, information on the present (10-15 yrs after the outburst) nature and structure of the object. We present and analyse a high-resolution (R = 21 000) spectrum of V4332 Sgr obtained with the Subaru Telescope in June 2009. Various components (stellar-like continuum, atomic emission lines, molecular bands in emission) in the spectrum are analysed and discussed. We also investigate a global spectral energy distribution (SED) of the object mostly derived from broadband optical and infrared photometry. The observed continuum resembles that of an M6 giant. The emission features (atomic and molecular) are most probably produced by radiative pumping. The observed strengths of the emission features strongly suggest that we observe only a small part of the radiation of the main object responsible for pumping the emission features. An infrared component seen in the observed SED, which can be roughly approximated by two blackbodies of 950 and 200 K, is 50 times brighter than the M6 stellar component seen in the optical. This further supports the idea that the main object is mostly obscured for us. The main object in V4332 Sgr, an M6 (super)giant, is surrounded by a circumstellar disc. The disc is seen almost edge-on so the central star is obscured. The observed M6 spectrum probably results from scattering the central star spectrum on dust grains at the outer edge of the disc.
VHE gamma-ray emission of PKS 2155-304: spectral and temporal variability
HESS Collaboration, Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Barres de Almeida, U., Bazer-Bachi, A. R., Becherini, Y., Behera, B., Benbow, W., Bernlohr, K., Bochow, A., Boisson, C., Bolmont, J., Borrel, V., Brucker, J., Brun, F., Brun, P., Buhler, R., Bulik, T., Busching, I., Boutelier, T., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Conrad, J., Chounet, L. -., Clapson, A. C., Coignet, G., Costamante, L., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Atai, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fiasson, A., Foerster, A., Fontaine, G., Fussling, M., Gabici, S., Gallant, Y. A., Gerard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glueck, B., Goret, P., Goering, D., Hampf, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jung, I., Katarzynski, K., Katz, U., Kaufmann, S., Kerschhaggl, M., Khangulyan, D., Khelifi, B., Keogh, D., Klochkov, D., Kluzniak, W., Kneiske, T., Komin, N., Kosack, K., Kossakowski, R., Lamanna, G., Lenain, J. -., Lohse, T., Lu, C. -., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., McComb, T. J. L., Medina, M. C., Mehault, J., Moderski, R., Moulin, E., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nguyen, N., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Olive, J., de Ona Wilhelmi, E., Opitz, B., Orford, K. J., Ostrowski, M., Panter, M., Paz Arribas, M., Pedaletti, G., Pelletier, G., Petrucci, P. -., Pita, S., Puehlhofer, G., Punch, M., Quirrenbach, A., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Renaud, M., de los Reyes, R., Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Ryde, F., Sahakian, V., Santangelo, A., Schlickeiser, R., Schoeck, F. M., Schoenwald, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sushch, I., Sikora, M., Skilton, J. L., Sol, H., Stawarz, L., Steenkamp, R., Stegmann, C., Stinzing, F., Superina, G., Szostek, A., Tam, P. H., Tavernet, J. -., Terrier, R., Tibolla, O., Tluczykont, M., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Venter, L., Vialle, J. P., Viana, A., Vincent, P., Vivier, M., Voelk, H. J., Volpe, F., Vorobiov, S., Wagner, S. J., Ward, M., Zdziarski, A. A., Zech, A., and Zechlin, H. -.
2010 , eprint arXiv:1005.3702
Abstract:
Observations of very high energy gamma-rays from blazars provide information about acceleration mechanisms occurring in their innermost regions. Studies of variability in these objects allow a better understanding of the mechanisms at play. To investigate the spectral and temporal variability of VHE (>100 GeV) gamma-rays of the well-known high-frequency-peaked BL Lac object PKS 2155-304 with the H.E.S.S. imaging atmospheric Cherenkov telescopes over a wide range of flux states. Data collected from 2005 to 2007 are analyzed. Spectra are derived on time scales ranging from 3 years to 4 minutes. Light curve variability is studied through doubling timescales and structure functions, and is compared with red noise process simulations. The source is found to be in a low state from 2005 to 2007, except for a set of exceptional flares which occurred in July 2006. The quiescent state of the source is characterized by an associated mean flux level of 4.32 +/-0.09 x 10^-11 cm^-2 s^-1 above 200 GeV, or approximately 15% of the Crab Nebula, and a power law photon index of 3.53 +/-0.06. During the flares of July 2006, doubling timescales of ~2 min are found. The spectral index variation is examined over two orders of magnitude in flux, yielding different behaviour at low and high fluxes,which is a new phenomenon in VHE gamma-ray emitting blazars. The variability amplitude characterized by the fractional r.m.s. is strongly energy-dependent and is proportional to E^(0.19 +/- 0.01). The light curve r.m.s. correlates with the flux. This is the signature of a multiplicative process which can be accounted for as a red noise with a Fourier index of ~2. This unique data set shows evidence for a low level gamma-ray emission state from PKS 2155-304, which possibly has a different origin than the outbursts. The discovery of the light curve lognormal behaviour might be an indicator ..
Water production in comet 81P/Wild 2 as determined by Herschel/HIFI
de Val-Borro, M., Hartogh, P., Crovisier, J., Bockelée-Morvan, D., Biver, N., Lis, D. C., Moreno, R., Jarchow, C., Rengel, M., Szutowicz, S., Banaszkiewicz, M., Bensch, F., Błęcka, M. I., Emprechtinger, M., Encrenaz, T., Jehin, E., Küppers, M., Lara, L. -., Lellouch, E., Swinyard, B. M., Vandenbussche, B., Bergin, E. A., Blake, G. A., Blommaert, J. A. D. L., Cernicharo, J., Decin, L., Encrenaz, P., de Graauw, T., Hutsemékers, D., Kidger, M., Manfroid, J., Medvedev, A. S., Naylor, D. A., Schieder, R., Stam, D., Thomas, N., Waelkens, C., Szczerba, R., Saraceno, P., Di Giorgio, A. M., Philipp, S., Klein, T., Ossenkopf, V., Zaal, P., and Shipman, R.
2010 , eprint arXiv:1007.0149
Abstract:
The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this letter we present HIFI observations of the fundamental 110-101 (557 GHz) ortho and 111-000 (1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and solar infrared radiation. We derive a mean water production rate of $1.0 imes 10^{28}$ molecules s$^{-1}$ at a heliocentric distance of 1.61 AU about 20 days before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes.
XMM-Newton Detection of a Delayed X-ray Eruption from V838 Monocerotis
Antonini, F., Montez, R., Jr., Kastner, J., Bond, H. E., Soker, N., Tylenda, R., and Starrfield, S.
2010 , American Astronomical Society, AAS Meeting #215, #385.08; Bulletin of the American Astronomical Society, Vol. 42, p.601
Abstract:
The star V838 Mon, discovered undergoing an outburst at the beginning of January 2002, is one of the most enigmatic objects observed in stellar astrophysics in recent decades.
We report the XMM-Newton/EPIC detection in 2008 March of a pair of spatially confused X-ray sources in the vicinity of V838 Mon. Spectral/spatial analysis demonstrates
the presence of a relatively hard, luminous source that is spatially coincident with V838 Mon itself, and a second, more luminous source located 8'' south of V838 Mon (projected separation 0.2pc if at the 6 kpc distance of V838 Mon). Neither source was detected in a Chandra/ACIS-S observation obtained about one year after outburst. The inferred X-ray luminosity and temperature of the hard source component at the position of V838 Mon, as well as its delayed appearance, appear consistent with a
stellar merger scenario for the optical/IR outburst of V838 Mon. Further X-ray observations of V838 Mon are warranted, to confirm the position(s) of the source(s) in the vicinity of V838 Mon and to establish their long- and short-term temporal behavior.This research has been supported via NASA/GSFC XMM/Newton Guest Observer Facility grant NNX08AD91G to RIT (and associated subcontracts to STScI and the University of Arizona).
XMM-Newton Detection of a Transient X-ray Source in the Vicinity of V838 Monocerotis
Antonini, F., Montez, R., Jr., Kastner, J. H., Bond, H. E., Soker, N., Tylenda, R., Starrfield, S., and Behar, E.
2010 , The Astrophysical Journal, Volume 717, Issue 2, pp. 795-802 (2010).
Abstract:
We report the XMM-Newton/EPIC detection in 2008 March of a luminous (LX ~ 1032-33 erg s–1), variable X-ray source in the vicinity (within ~6'') of the enigmatic star V838 Mon, which underwent a spectacular outburst in early 2002. Spectral modeling of the XMM-Newton X-ray source indicates the presence of two plasma components with characteristic temperatures of TX ~ 2 × 106 K and ~1.5 × 107 K, attenuated by an absorbing column (NH ~ 4 × 1021 cm–2) that is consistent with the visual extinction measured toward V838 Mon (AV ~ 2). No such luminous source was detected in the immediate vicinity of V838 Mon in Chandra/ACIS-S observations obtained about one year after outburst or, most recently, in 2010 January. The two XMM -Newton source spectral components appear to be marginally spatially resolved, with the spatial centroid of the hard component lying closer to (within ~2'' of) the position of V838 Mon than the broadband source or the soft source component; however, if there are two sources at or near V838 Mon, the Chandra nondetections would imply that both of them are variable. An alternative is that there is a single variable source, and that the apparent spatial separation may actually be due to photon-counting statistics or is perhaps instrumental in origin. We consider constraints placed by the X-ray detection and nondetections on a stellar merger model for the 2002 V838 Mon outburst, in which the spun-up merger product drives a powerful magnetic dynamo. Alternatively, the transient behavior of the X-ray source could indicate that the X-rays arose as a consequence of an interaction between V838 Mon's ejecta and its early-type (B3 V) companion.
Formation of Fullerenes in H-containing Planetary Nebulae
García-Hernández, D. A., Manchado, A., García-Lario, P., Stanghellini, L., Villaver, E., Shaw, R. A., Szczerba, R., Perea-Calderón, J. V.
2010, The Astrophysical Journal Letters, Volume 724, Issue 1, pp. L39-L43 (2010).
Abstract:
Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C60 and C70 fullerenes in what was interpreted as the hydrogen-poor inner region of a post-final helium shell flash planetary nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of polycyclic aromatic hydrocarbons (PAHs) and fullerenes toward C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations suggest that modifications may be needed to our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.
Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI
Harwit, M., Houde, M., Sonnentrucker, P., Boogert, A. C. A., Cernicharo, J., de Beck, E., Decin, L., Henkel, C., Higgins, R. D., Jellema, W., Kraus, A., McCoey, C., Melnick, G. J., Menten, K. M., Risacher, C., Teyssier, D., Vaillancourt, J. E., Alcolea, J., Bujarrabal, V., Dominik, C., Justtanont, K., de Koter, A., Marston, A. P., Olofsson, H., Planesas, P., Schmidt, M., Schöier, F. L., Szczerba, R., Waters, L. B. F. M.
2010, Astronomy and Astrophysics, Volume 521, id.L51
Abstract:

Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight.

Aims. We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O.

Methods. In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s-1, which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut für Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission.

Results. We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix (page 5) is only available in electronic form at http://www.aanda.org
Water production in comet 81P/Wild 2 as determined by Herschel/HIFI
de Val-Borro, M., Hartogh, P., Crovisier, J., Bockelée-Morvan, D., Biver, N., Lis, D. C., Moreno, R., Jarchow, C., Rengel, M., Szutowicz, S., Banaszkiewicz, M., Bensch, F., Błęcka, M. I., Emprechtinger, M., Encrenaz, T., Jehin, E., Küppers, M., Lara, L.-M., Lellouch, E., Swinyard, B. M., Vandenbussche, B., Bergin, E. A., Blake, G. A., Blommaert, J. A. D. L., Cernicharo, J., Decin, L., Encrenaz, P., de Graauw, T., Hutsemékers, D., Kidger, M., Manfroid, J., Medvedev, A. S., Naylor, D. A., Schieder, R., Stam, D., Thomas, N., Waelkens, C., Szczerba, R., Saraceno, P., di Giorgio, A. M., Philipp, S., Klein, T., Ossenkopf, V., Zaal, P., Shipman, R.
2010, Astronomy and Astrophysics, Volume 521, id.L50
Abstract:
The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this Letter we present HIFI observations of the fundamental 110-101 (557 GHz) ortho and 111-00 (1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and solar infrared radiation. We derive a mean water production rate of 1.0 × 1028 molecules s-1 at a heliocentric distance of 1.61 AU about 20 days before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figure 5 (page 5) is only available in electronic form at http://www.aanda.org
Detection of OH+ and H2O+ towards Orion KL
Gupta, H., Rimmer, P., Pearson, J. C., Yu, S., Herbst, E., Harada, N., Bergin, E. A., Neufeld, D. A., Melnick, G. J., Bachiller, R., Baechtold, W., Bell, T. A., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Chattopadhyay, G., Comito, C., Cabrit, S., Crockett, N. R., Daniel, F., Falgarone, E., Diez-Gonzalez, M. C., Dubernet, M.-L., Erickson, N., Emprechtinger, M., Encrenaz, P., Gerin, M., Gill, J. J., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Joblin, C., Johnstone, D., Langer, W. D., Larsson, B., Latter, W. B., Lin, R. H., Lis, D. C., Liseau, R., Lord, S. D., Maiwald, F. W., Maret, S., Martin, P. G., Martin-Pintado, J., Menten, K. M., Morris, P., Müller, H. S. P., Murphy, J. A., Nordh, L. H., Olberg, M., Ossenkopf, V., Pagani, L., Pérault, M., Phillips, T. G., Plume, R., Qin, S.-L., Salez, M., Samoska, L. A., Schilke, P., Schlecht, E., Schlemmer, S., Szczerba, R., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Zmuidzinas, J., Boogert, A., Güsten, R., Hartogh, P., Honingh, N., Karpov, A., Kooi, J., Krieg, J.-M., Schieder, R., Zaal, P.
2010, Astronomy and Astrophysics, Volume 521, id.L47
Abstract:
We report observations of the reactive molecular ions OH+, H2O+, and H3O+ towards Orion KL with Herschel/HIFI. All three N = 1-0 fine-structure transitions of OH+ at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H2O+ 111-000 transition at 1115 and 1139 GHz were detected; an upper limit was obtained for H3O+. OH+ and H2O+ are observed purely in absorption, showing a narrow component at the source velocity of 9 km s-1, and a broad blueshifted absorption similar to that reported recently for HF and para-H218O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH+ and H2O+ for the 9 km s-1 component of 9 ± 3 × 1012 cm-2 and 7 ± 2 × 1012 cm-2, and those in the outflow of 1.9 ± 0.7 × 1013 cm-2 and 1.0 ± 0.3 × 1013 cm-2. Upper limits of 2.4 × 1012 cm-2 and 8.7 × 1012 cm-2 were derived for the column densities of ortho and para-H3O+ from transitions near 985 and 1657 GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate.
Herschel observations of deuterated water towards Sgr B2(M)
Comito, C., Schilke, P., Rolffs, R., Lis, D. C., Belloche, A., Bergin, E. A., Phillips, T. G., Bell, T. A., Crockett, N. R., Wang, S., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Müller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Pérault, M., Plume, R., Qin, S.-L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Olberg, M., Szczerba, R., Larsson, B., Liseau, R., Lin, R. H., Samoska, L. A., Schlecht, E.
2010, Astronomy and Astrophysics, Volume 521, id.L38
Abstract:
Observations of HDO are an important complement for studies of water, because they give strong constraints on the formation processes - grain surfaces versus energetic process in the gas phase, e.g. in shocks. The HIFI observations of multiple transitions of HDO in Sgr B2(M) presented here allow the determination of the HDO abundance throughout the envelope, which has not been possible before with ground-based observations only. The abundance structure has been modeled with the spherical Monte Carlo radiative transfer code RATRAN, which also takes radiative pumping by continuum emission from dust into account. The modeling reveals that the abundance of HDO rises steeply with temperature from a low abundance (2.5 × 10-11) in the outer envelope at temperatures below 100 K through a medium abundance (1.5 × 10-9) in the inner envelope/outer core at temperatures between 100 and 200 K, and finally a high abundance (3.5 × 10-9) at temperatures above 200 K in the hot core. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Water in massive star-forming regions: HIFI observations of W3 IRS5
Chavarría, L., Herpin, F., Jacq, T., Braine, J., Bontemps, S., Baudry, A., Marseille, M., van der Tak, F., Pietropaoli, B., Wyrowski, F., Shipman, R., Frieswijk, W., van Dishoeck, E. F., Cernicharo, J., Bachiller, R., Benedettini, M., Benz, A. O., Bergin, E., Bjerkeli, P., Blake, G. A., Bruderer, S., Caselli, P., Codella, C., Daniel, F., di Giorgio, A. M., Dominik, C., Doty, S. D., Encrenaz, P., Fich, M., Fuente, A., Giannini, T., Goicoechea, J. R., de Graauw, T., Hartogh, P., Helmich, F., Herczeg, G. J., Hogerheijde, M. R., Johnstone, D., Jørgensen, J. K., Kristensen, L. E., Larsson, B., Lis, D., Liseau, R., McCoey, C., Melnick, G., Nisini, B., Olberg, M., Parise, B., Pearson, J. C., Plume, R., Risacher, C., Santiago-García, J., Saraceno, P., Stutzki, J., Szczerba, R., Tafalla, M., Tielens, A., van Kempen, T. A., Visser, R., Wampfler, S. F., Willem, J., Yıldız, U. A.
2010, Astronomy and Astrophysics, Volume 521, id.L37
Abstract:
We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H_217O 110-101, p-H_218O 111-000, p-H2O 202-111, p-H2O 111-000, o-H2O 221-212, and o-H2O 212-101 lines, covering a frequency range from 552 up to 1669 GHz, have been detected at high spectral resolution with HIFI. The water lines in W3 IRS5 show well-defined high-velocity wings that indicate a clear contribution by outflows. Moreover, the systematically blue-shifted absorption in the H2O lines suggests expansion, presumably driven by the outflow. No infall signatures are detected. The p-H2O 111-000 and o-H2O 212-101 lines show absorption from the cold material (T ~ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T ≳ 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10-4) is needed to reproduce the o-H_217O 110-101 and p-H_218O 111-000 spectra in our models. We estimate water abundances of 10-8 to 10-9 in the outer parts of the envelope (T ≲ 100 K). The possibility of two protostellar objects contributing to the emission is discussed. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Sensitive limits on the abundance of cold water vapor in the DM Tauri protoplanetary disk
Bergin, E. A., Hogerheijde, M. R., Brinch, C., Fogel, J., Yıldız, U. A., Kristensen, L. E., van Dishoeck, E. F., Bell, T. A., Blake, G. A., Cernicharo, J., Dominik, C., Lis, D., Melnick, G., Neufeld, D., Panić, O., Pearson, J. C., Bachiller, R., Baudry, A., Benedettini, M., Benz, A. O., Bjerkeli, P., Bontemps, S., Braine, J., Bruderer, S., Caselli, P., Codella, C., Daniel, F., di Giorgio, A. M., Doty, S. D., Encrenaz, P., Fich, M., Fuente, A., Giannini, T., Goicoechea, J. R., de Graauw, T., Helmich, F., Herczeg, G. J., Herpin, F., Jacq, T., Johnstone, D., Jørgensen, J. K., Larsson, B., Liseau, R., Marseille, M., McCoey, C., Nisini, B., Olberg, M., Parise, B., Plume, R., Risacher, C., Santiago-García, J., Saraceno, P., Shipman, R., Tafalla, M., van Kempen, T. A., Visser, R., Wampfler, S. F., Wyrowski, F., van der Tak, F., Jellema, W., Tielens, A. G. G. M., Hartogh, P., Stützki, J., Szczerba, R.
2010, Astronomy and Astrophysics, Volume 521, id.L33
Abstract:
We performed a sensitive search for the ground-state emission lines of ortho- and para-water vapor in the DM Tau protoplanetary disk using the Herschel/HIFI instrument. No strong lines are detected down to 3σ levels in 0.5 km s-1 channels of 4.2 mK for the 110-101 line and 12.6 mK for the 111-000 line. We report a very tentative detection, however, of the 110-101 line in the wide band spectrometer, with a strength of Tmb = 2.7 mK, a width of 5.6 km s-1 and an integrated intensity of 16.0 mK km s-1. The latter constitutes a 6σ detection. Regardless of the reality of this tentative detection, model calculations indicate that our sensitive limits on the line strengths preclude efficient desorption of water in the UV illuminated regions of the disk. We hypothesize that more than 95-99% of the water ice is locked up in coagulated grains that have settled to the midplane. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with participation important from NASA.
Herschel observations in the ultracompact HII region Mon R2. Water in dense photon-dominated regions (PDRs)
Fuente, A., Berné, O., Cernicharo, J., Rizzo, J. R., González-García, M., Goicoechea, J. R., Pilleri, P., Ossenkopf, V., Gerin, M., Güsten, R., Akyilmaz, M., Benz, A. O., Boulanger, F., Bruderer, S., Dedes, C., France, K., García-Burillo, S., Harris, A., Joblin, C., Klein, T., Kramer, C., Le Petit, F., Lord, S. D., Martin, P. G., Martín-Pintado, J., Mookerjea, B., Neufeld, D. A., Okada, Y., Pety, J., Phillips, T. G., Röllig, M., Simon, R., Stutzki, J., van der Tak, F., Teyssier, D., Usero, A., Yorke, H., Schuster, K., Melchior, M., Lorenzani, A., Szczerba, R., Fich, M., McCoey, C., Pearson, J., Dieleman, P.
2010, Astronomy and Astrophysics, Volume 521, id.L23
Abstract:

Context. Monoceros R2, at a distance of 830 pc, is the only ultracompact H ii region (UC H ii) where the photon-dominated region (PDR) between the ionized gas and the molecular cloud can be resolved with Herschel. Therefore, it is an excellent laboratory to study the chemistry in extreme PDRs (G0 > 105 in units of Habing field, n > 106 cm-3).

Aims. Our ultimate goal is to probe the physical and chemical conditions in the PDR around the UC H ii Mon R2.

Methods. HIFI observations of the abundant compounds 13CO, C18O, o-H218O, HCO+, CS, CH, and NH have been used to derive the physical and chemical conditions in the PDR, in particular the water abundance. The modeling of the lines has been done with the Meudon PDR code and the non-local radiative transfer model described by Cernicharo et al.

Results. The 13CO, C18O, o-H_218O, HCO+ and CS observations are well described assuming that the emission is coming from a dense (n = 5 × 106 cm-3, N(H2)> 1022 cm-2) layer of molecular gas around the H ii region. Based on our o-H_218O observations, we estimate an o-H2O abundance of ≈2 × 10-8. This is the average ortho-water abundance in the PDR. Additional H_218O and/or water lines are required to derive the water abundance profile. A lower density envelope (n ~ 105 cm-3, N(H2) = 2-5 × 1022 cm-2) is responsible for the absorption in the NH 1_1→ 0_2 line. The emission of the CH ground state triplet is coming from both regions with a complex and self-absorbed profile in the main component. The radiative transfer modeling shows that the 13CO and HCO+ line profiles are consistent with an expansion of the molecular gas with a velocity law, ve = 0.5 × (r/Rout)-1 km s-1, although the expansion velocity is poorly constrained by the observations presented here.

Conclusions. We determine an ortho-water abundance of ≈2 × 10-8 in Mon R2. Because shocks are unimportant in this region and our estimate is based on H_218O observations that avoids opacity problems, this is probably the most accurate estimate of the water abundance in PDRs thus far. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figures 1 and 4 (page 5) are only available in electronic form at http://www.aanda.org
Herschel/HIFI observations of interstellar OH+ and H2O+ towards W49N: a probe of diffuse clouds with a small molecular fraction
Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., Black, J. H., Pearson, J., Yu, S., Phillips, T. G., Lis, D. C., de Luca, M., Herbst, E., Rimmer, P., Gerin, M., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Joblin, C., Kołos, R., Krełowski, J., Martín-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Cros, A., Klein, K., Lorenzani, A., Philipp, S., Samoska, L. A., Shipman, R., Tielens, A. G. G. M., Szczerba, R., Zmuidzinas, J.
2010, Astronomy and Astrophysics, Volume 521, id.L10
Abstract:
We report the detection of absorption by interstellar hydroxyl cations and water cations, along the sight-line to the bright continuum source W49N. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 972 GHz N = 1-0 transition of OH+ and the 1115 GHz 111-000 transition of ortho-H2O+. The resultant spectra show absorption by ortho-H2O+, and strong absorption by OH+, in foreground material at velocities in the range 0 to 70 km s-1 with respect to the local standard of rest. The inferred OH+/H2O+ abundance ratio ranges from ~3 to ~15, implying that the observed OH+ arises in clouds of small molecular fraction, in the 2-8% range. This conclusion is confirmed by the distribution of OH+ and H2O+ in Doppler velocity space, which is similar to that of atomic hydrogen, as observed by means of 21 cm absorption measurements, and dissimilar from that typical of other molecular tracers. The observed OH+/H abundance ratio of a few × 10-8 suggests a cosmic ray ionization rate for atomic hydrogen of 0.6-2.4×10-16 s-1, in good agreement with estimates inferred previously for diffuse clouds in the Galactic disk from observations of interstellar H3+ and other species. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Herschel/HIFI deepens the circumstellar NH3 enigma
Menten, K. M., Wyrowski, F., Alcolea, J., de Beck, E., Decin, L., Marston, A. P., Bujarrabal, V., Cernicharo, J., Dominik, C., Justtanont, K., de Koter, A., Melnick, G., Neufeld, D. A., Olofsson, H., Planesas, P., Schmidt, M., Schöier, F. L., Szczerba, R., Teyssier, D., Waters, L. B. F. M., Edwards, K., Olberg, M., Phillips, T. G., Morris, P., Salez, M., Caux, E.
2010, Astronomy and Astrophysics, Volume 521, id.L7
Abstract:

Context. Circumstellar envelopes (CSEs) of a variety of evolved stars have been found to contain ammonia (NH3) in amounts that exceed predictions from conventional chemical models by many orders of magnitude.

Aims. The observations reported here were performed in order to better constrain the NH3 abundance in the CSEs of four, quite diverse, oxygen-rich stars using the NH3 ortho JK = 10-00 ground-state line.

Methods. We used the Heterodyne Instrument for the Far Infrared aboard Herschel to observe the NH3 JK = 10-00 transition near 572.5 GHz, simultaneously with the ortho-H2O JKa , Kc = 11,0 - 10,1 transition, toward VY CMa, OH 26.5+0.6, IRC+10420, and IK Tau. We conducted non-LTE radiative transfer modeling with the goal to derive the NH3 abundance in these objects' CSEs. For the last two stars, Very Large Array imaging of NH3 radio-wavelength inversion lines were used to provide further constraints, particularly on the spatial extent of the NH3-emitting regions.

Results. We find remarkably strong NH3 emission in all of our objects with the NH3 line intensities rivaling those of the ground state H2O line. The NH3 abundances relative to H2 are very high and range from 2×10-7 to 3×10-6 for the objects we have studied.

Conclusions. Our observations confirm and even deepen the circumstellar NH3 enigma. While our radiative transfer modeling does not yield satisfactory fits to the observed line profiles, it does lead to abundance estimates that confirm the very high values found in earlier studies. New ways to tackle this mystery will include further Herschel observations of more NH3 lines and imaging with the Expanded Very Large Array. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A (page 5) is only available in electronic form at http://www.aanda.org
A HIFI preview of warm molecular gas around χ Cygni: first detection of H2O emission toward an S-type AGB star
Justtanont, K., Decin, L., Schöier, F. L., Maercker, M., Olofsson, H., Bujarrabal, V., Marston, A. P., Teyssier, D., Alcolea, J., Cernicharo, J., Dominik, C., de Koter, A., Melnick, G., Menten, K., Neufeld, D., Planesas, P., Schmidt, M., Szczerba, R., Waters, R., de Graauw, T., Whyborn, N., Finn, T., Helmich, F., Siebertz, O., Schmülling, F., Ossenkopf, V., Lai, R.
2010, Astronomy and Astrophysics, Volume 521, id.L6
Abstract:


Aims. A set of new, sensitive, and spectrally resolved, sub-millimeter line observations are used to probe the warm circumstellar gas around the S-type AGB star χ Cyg. The observed lines involve high rotational quantum numbers, which, combined with previously obtained lower-frequency data, make it possible to study in detail the chemical and physical properties of, essentially, the entire circumstellar envelope of χ Cyg.

Methods. The data were obtained using the HIFI instrument aboard Herschel, whose high spectral resolution provides valuable information about the line profiles. Detailed, non-LTE, radiative transfer modelling, including dust radiative transfer coupled with a dynamical model, has been performed to derive the temperature, density, and velocity structure of the circumstellar envelope.

Results. We report the first detection of circumstellar H2O rotational emission lines in an S-star. Using the high-J CO lines to derive the parameters for the circumstellar envelope, we modelled both the ortho- and para-H2O lines. Our modelling results are consistent with the velocity structure expected for a dust-driven wind. The derived total H2O abundance (relative to H2) is (1.1±0.2) × 10-5, much lower than that in O-rich stars. The derived ortho-to-para ratio of 2.1±0.6 is close to the high-temperature equilibrium limit, consistent with H2O being formed in the photosphere. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Discovery of water vapour in the carbon star V Cygni from observations with Herschel/HIFI
Neufeld, D. A., González-Alfonso, E., Melnick, G., Pułecka, M., Schmidt, M., Szczerba, R., Bujarrabal, V., Alcolea, J., Cernicharo, J., Decin, L., Dominik, C., Justtanont, K., de Koter, A., Marston, A. P., Menten, K., Olofsson, H., Planesas, P., Schöier, F. L., Teyssier, D., Waters, L. B. F. M., Edwards, K., McCoey, C., Shipman, R., Jellema, W., de Graauw, T., Ossenkopf, V., Schieder, R., Philipp, S.
2010, Astronomy and Astrophysics, Volume 521, id.L5
Abstract:
We report the discovery of water vapour toward the carbon star V Cygni. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 111-000 para-water transition at 1113.3430 GHz in the upper sideband of the Band 4b receiver. The observed spectral line profile is nearly parabolic, but with a slight asymmetry associated with blueshifted absorption, and the integrated antenna temperature is 1.69 ± 0.17 K km s-1. This detection of thermal water vapour emission, carried out as part of a small survey of water in carbon-rich stars, is only the second such detection toward a carbon-rich AGB star, the first having been obtained by the Submillimeter Wave Astronomy Satellite toward IRC+10216. For an assumed ortho-to-para ratio of 3 for water, the observed line intensity implies a water outflow rate ~3-6 × 10-5 Earth masses per year and a water abundance relative to H2 of ~2-5 × 10-6. This value is a factor of at least 104 larger than the expected photospheric abundance in a carbon-rich environment, and - as in IRC+10216 - raises the intriguing possibility that the observed water is produced by the vapourisation of orbiting comets or dwarf planets. However, observations of the single line observed to date do not permit us to place strong constraints upon the spatial distribution or origin of the observed water, but future observations of additional transitions will allow us to determine the inner radius of the H2O-emitting zone, and the H2O ortho-to-para ratio, and thereby to place important constraints upon the origin of the observed water emission. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI
Decin, L., Justtanont, K., de Beck, E., Lombaert, R., de Koter, A., Waters, L. B. F. M., Marston, A. P., Teyssier, D., Schöier, F. L., Bujarrabal, V., Alcolea, J., Cernicharo, J., Dominik, C., Melnick, G., Menten, K., Neufeld, D. A., Olofsson, H., Planesas, P., Schmidt, M., Szczerba, R., de Graauw, T., Helmich, F., Roelfsema, P., Dieleman, P., Morris, P., Gallego, J. D., Díez-González, M. C., Caux, E.
2010, Astronomy and Astrophysics, Volume 521, id.L4
Abstract:
During their asymptotic giant branch evolution, low-mass stars lose a significant fraction of their mass through an intense wind, enriching the interstellar medium with products of nucleosynthesis. We observed the nearby oxygen-rich asymptotic giant branch star IK Tau using the high-resolution HIFI spectrometer onboard Herschel. We report on the first detection of H_216O and the rarer isotopologues H_217O and H_218O in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of 6.6 × 10-5, and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H2O in thermodynamical chemical equilibrium at photospheric temperatures, and does not require pulsationally induced non-equilibrium chemistry, vaporization of icy bodies or grain surface reactions. High-excitation lines of 12CO, 13CO, 28SiO, 29SiO, 30SiO, HCN, and SO have also been detected. From the observed line widths, the acceleration region in the inner wind zone can be characterized, and we show that the wind acceleration is slower than hitherto anticipated. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices (pages 6 and 7) are only available in electronic form at http://www.aanda.org
Herschel/HIFI observations of high-J CO transitions in the protoplanetary nebula CRL 618
Bujarrabal, V., Alcolea, J., Soria-Ruiz, R., Planesas, P., Teyssier, D., Marston, A. P., Cernicharo, J., Decin, L., Dominik, C., Justtanont, K., de Koter, A., Melnick, G., Menten, K. M., Neufeld, D. A., Olofsson, H., Schmidt, M., Schöier, F. L., Szczerba, R., Waters, L. B. F. M., Quintana-Lacaci, G., Güsten, R., Gallego, J. D., Díez-González, M. C., Barcia, A., López-Fernández, I., Wildeman, K., Tielens, A. G. G. M., Jacobs, K.
2010, Astronomy and Astrophysics, Volume 521, id.L3
Abstract:


Aims. We aim to study the physical conditions, particularly the excitation state, of the intermediate-temperature gas components in the protoplanetary nebula CRL 618. These components are particularly important for understanding the evolution of the nebula.

Methods. We performed Herschel/HIFI observations of several CO lines in the far-infrared/sub-mm in the protoplanetary nebula CRL 618. The high spectral resolution provided by HIFI allows measurement of the line profiles. Since the dynamics and structure of the nebula is well known from mm-wave interferometric maps, it is possible to identify the contributions of the different nebular components (fast bipolar outflows, double shells, compact slow shell) to the line profiles. The observation of these relatively high-energy transitions allows an accurate study of the excitation conditions in these components, particularly in the warm ones, which cannot be properly studied from the low-energy lines.

Results. The 12CO J = 16-15, 10-9, and 6-5 lines are easily detected in this source. Both 13CO J = 10-9 and 6-5 are also detected. Wide profiles showing spectacular line wings have been found, particularly in 12CO J = 16-15. Other lines observed simultaneously with CO are also shown. Our analysis of the CO high-J transitions, when compared with the existing models, confirms the very low expansion velocity of the central, dense component, which probably indicates that the shells ejected during the last AGB phases were driven by radiation pressure under a regime of maximum transfer of momentum. No contribution of the diffuse halo found from mm-wave data is identified in our spectra, because of its low temperature. We find that the fast bipolar outflow is quite hot, much hotter than previously estimated; for instance, gas flowing at 100 km s-1 must have a temperature higher than ~200 K. Probably, this very fast outflow, with a kinematic age <100 yr, has been accelerated by a shock and has not yet cooled down. The double empty shell found from mm-wave mapping must also be relatively hot, in agreement with the previous estimate. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Excitation of the molecular gas in the nuclear region of M 82
Loenen, A. F., van der Werf, P. P., Güsten, R., Meijerink, R., Israel, F. P., Requena-Torres, M. A., García-Burillo, S., Harris, A. I., Klein, T., Kramer, C., Lord, S., Martín-Pintado, J., Röllig, M., Stutzki, J., Szczerba, R., Weiß, A., Philipp-May, S., Yorke, H., Caux, E., Delforge, B., Helmich, F., Lorenzani, A., Morris, P., Philips, T. G., Risacher, C., Tielens, A. G. G. M.
2010, Astronomy and Astrophysics, Volume 521, id.L2
Abstract:
We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M 82. Six 12CO lines, 2 13CO lines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 103.5 cm-3) clouds, with column densities of NH = 1021.5 cm-2 and a relatively low UV radiation field (G0 = 102). The remaining gas is predominantly found in clouds with higher densities (n = 105 cm-3) and radiation fields (G0 = 102.75), but somewhat lower column densities (NH = 1021.2 cm-2). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 106 cm-3) and UV field (G0 = 103.25). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies.
HIFI spectroscopy of low-level water transitions in M 82
Weiß, A., Requena-Torres, M. A., Güsten, R., García-Burillo, S., Harris, A. I., Israel, F. P., Klein, T., Kramer, C., Lord, S., Martin-Pintado, J., Röllig, M., Stutzki, J., Szczerba, R., van der Werf, P. P., Philipp-May, S., Yorke, H., Akyilmaz, M., Gal, C., Higgins, R., Marston, A., Roberts, J., Schlöder, F., Schultz, M., Teyssier, D., Whyborn, N., Wunsch, H. J.
2010, Astronomy and Astrophysics, Volume 521, id.L1
Abstract:
We present observations of the rotational ortho-water ground transition, the two lowest para-water transitions, and the ground transition of ionised ortho-water in the archetypal starburst galaxy M 82, performed with the HIFI instrument on the Herschel Space Observatory. These observations are the first detections of the para-H2O(111-000) (1113 GHz) and ortho-H2O+(111-000) (1115 GHz) lines in an extragalactic source. All three water lines show different spectral line profiles, underlining the need for high spectral resolution in interpreting line formation processes. Using the line shape of the para-H2O(111-000) and ortho-H2O+(111-000) absorption profile in conjunction with high spatial resolution CO observations, we show that the (ionised) water absorption arises from a ~2000 pc2 region within the HIFI beam located about ~50 pc east of the dynamical centre of the galaxy. This region does not coincide with any of the known line emission peaks that have been identified in other molecular tracers, with the exception of HCO. Our data suggest that water and ionised water within this region have high (up to 75%) area-covering factors of the underlying continuum. This indicates that water is not associated with small, dense cores within the ISM of M 82 but arises from a more widespread diffuse gas component. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with participation from NASA.
New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge
Górny, S. K., Perea-Calderón, J. V., García-Hernández, D. A., García-Lario, P., Szczerba, R.
2010, Astronomy and Astrophysics, Volume 516, id.A39
Abstract:


Aims. We investigate Galactic bulge planetary nebulae without emission-line central stars for which peculiar infrared spectra have been obtained with the Spitzer Space Telescope, including the simultaneous signs of oxygen and carbon based dust. Three separate sub-groups can be defined characterized by the different chemical composition of the dust and the presence of crystalline and amorphous silicates.

Methods. We use literature data to analyze the different nebular properties and deduce both the evolutionary status and the origin of these three groups. In particular, we check whether there are signs of evolutionary links between dual-dust chemistry planetary nebulae without detected emission-line central stars and those with emission-line stars.

Results. Our primary finding is that the classification based on the dust properties is reflected in the more general properties of these planetary nebulae. However, some observed properties are difficult to relate to the common view of planetary nebulae. In particular, it is challenging to interpret the peculiar gas chemical composition of many analyzed objects in the standard picture of the evolution of planetary nebulae progenitors. We confirm that the dual-dust chemistry phenomenon is not limited to planetary nebulae with emission-line central stars.

Conclusions. Our results clearly indicate that there is no unique road to the formation of planetary nebulae even in a homogeneous environment such as the Galactic bulge. The evolution of a single asymptotic giant branch star may lead to the formation of different types of planetary nebulae. In addition, the evolution in a close binary system should sometimes also be considered. Based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.
© Nicolaus Copernicus Astronomical Center, Toruń