Publikacje w roku 2007
Dust Distribution in [WR] Planetary Nebulae: a Case of M2-43
Hajduk, M., Szczerba, R., and Gesicki, K.
2007 , Baltic Astronomy, Vol. 16, p. 151-154
Abstract:
Simultaneous presence of O- and C-rich molecules and/or dust is commonly known as mixed or dual chemistry. C-rich [WR] central stars show at the same time the presence of polycyclic aromatic hydrocarbons (PAHs) and crystalline silicates in their nebulae. We perform radiative transfer modeling of ISO spectrum for M2-43 to determine spatial location of PAHs and crystalline silicates inside the nebula. This allows us to discuss the origin of mixed chemistry in [WR] planetary nebulae.
Discovery of VHE γ-rays from the distant BL Lacertae 1ES 0347-121
Aharonian, F., Akhperjanian, A. G., Barres de Almeida, U., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Clapson, A. C., Coignet, G., Cornils, R., Costamante, L., Dalton, M., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., 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., Jung, I., Katarzyński, K., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Keogh, D., Komin, N., Kosack, K., Lamanna, G., Latham, I. J., Lemière, A., Lemoine-Goumard, M., Lenain, J.-P., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, D., Maurin, G., McComb, T. J. L., Moderski, R., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Ohm, S., Olive, J.-P., de Oña Wilhelmi, E., Orford, K. J., Osborne, J. L., Ostrowski, M., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Renaud, M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Rudak, B., Ruppel, J., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Stawarz, Ł., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2007 , Astronomy and Astrophysics, Volume 473, Issue 3, October III 2007, pp.L25-L28
Abstract:
Aims:Our aim is to study the production mechanism for very-high-energy (VHE; >100 GeV) γ-rays in distant active galactic nuclei (AGN) and use the observed VHE spectrum to derive limits on the Extragalactic Background Light (EBL). We also want to determine physical quantities through the modeling of the object's broad-band spectral energy distribution (SED).

Methods. VHE observations (~25 h live time) of the BL Lac 1ES 0347-121 (redshift z = 0.188) were conducted with the High Energy Stereoscopic System (HESS) between August and December 2006. Contemporaneous X-ray and UV/optical observations from the SWIFT satellite are used to interpret the SED of the source in terms of a synchrotron self Compton (SSC) model.

Results. An excess of 327 events, corresponding to a statistical significance of 10.1 standard deviations, is detected from 1ES 0347-121. Its photon spectrum, ranging from ~250 GeV to ~3 TeV, is well described by a power law with a photon index of Γ = 3.10 ± 0.23stat ± 0.10sys. The integral flux above 250 GeV corresponds to ~2% of the flux of the Crab Nebula above the same threshold. No VHE flux variability is detected within the data set.

Conclusions. Constraints on the EBL density at optical to near-infrared wavelengths derived from the photon spectrum of 1ES 0347-121 are close to the strongest limits derived previously. The strong EBL limits confirm earlier findings, that the EBL density in the near-infrared is close to the lower limits from source counts. This implies that the universe is more transparent to VHE γ-rays than previously believed. An SSC model provides a reasonable description of the contemporaneous SED.
Affiliations are only available in electronic form at http://www.aanda.org
An evolutionary catalogue of galactic post-AGB and related objects
Szczerba, R., Siódmiak, N., Stasińska, G., and Borkowski, J.
2007 , Astronomy and Astrophysics, Volume 469, Issue 2, July II 2007, pp.799-806
Abstract:
Aims:With the ongoing AKARI infrared sky survey, of much greater sensitivity than IRAS, a wealth of post-AGB objects may be discovered. It is thus time to organize our present knowledge of known post-AGB stars in the galaxy with a view to using it to search for new post-AGB objects among AKARI sources.

Methods. We searched the literature available on the NASA Astrophysics Data System up to 1 October 2006, and defined criteria for classifying sources into three categories: very likely, possible and disqualified post-AGB objects. The category of very likely post-AGB objects is made up of several classes.

Results. We have created an evolutionary, on-line catalogue of Galactic post-AGB objects, to be referred to as the Toruń catalogue of Galactic post-AGB and related objects. The present version of the catalogue contains 326 very likely, 107 possible and 64 disqualified objects. For the very likely post-AGB objects, the catalogue gives the available optical and infrared photometry, infrared spectroscopy and spectral types, and links to finding charts and bibliography.
A stable version of the catalogue is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/469/799
An Evolving Catalogue of Post-AGB and Related Objects
Szczerba, R., Siódmiak, N., Stasinska, G., and Borkowski, J.
2007 , Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes. ASP Conference Series, Vol. 378, proceedings of the conference held 7-11 August 2006 at University Campus, Vienna, Austria. Edited by F. Kerschbaum, C. Charbonnel, and R. F. Wing. San Francisco: Astronomical Society of the Pacific, 2007., p.465
Abstract:
We have created a catalogue containing more than 320 confirmed and about 110 candidate post-AGB stars and related objects. At the same time we have disqualified more than 60 objects which are/were sometimes called ``post-AGB.'' The on-line catalogue can be reached at http://www.ncac.torun.pl/ postagb.
An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304
Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Boutelier, T., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Bulik, T., Carrigan, S., Chadwick, P. M., Clapson, A. C., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O., Dubus, G., Dyks, J., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, S., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., 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., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, N., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lenain, J.-P., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moderski, R., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Olive, J.-P., Orford, K. J., Osborne, J. L., Ostrowski, M., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Renaud, M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Rudak, B., Ruppel, J., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Stawarz, Ł., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Wagner, S. J., Ward, M., and Zdziarski, A. A.
2007 , The Astrophysical Journal, Volume 664, Issue 2, pp. L71-L74.
Abstract:
The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.116 is a well-known VHE (>100 GeV) γ-ray emitter. Since 2002 its VHE flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric Cerenkov telescopes in Namibia. During the 2006 July dark period, the average VHE flux was measured to be more than 10 times typical values observed from the object. This article focuses solely on an extreme γ-ray outburst detected in the early hours of 2006 July 28 (MJD 53,944). The average flux observed during this outburst is I(>200 GeV) =(1.72+/-0.05stat+/-0.34syst)×10-9 cm-2 s-1, corresponding to ~7 times the flux, I(>200 GeV), observed from the Crab Nebula. Peak fluxes are measured with 1 minute timescale resolution at more than twice this average value. Variability is seen up to ~600 s in the Fourier power spectrum, and well-resolved bursts varying on timescales of ~200 s are observed. There are no strong indications for spectral variability within the data. Assuming the emission region has a size comparable to the Schwarzschild radius of a ~109 Msolar black hole, Doppler factors greater than 100 are required to accommodate the observed variability timescales.
A model for double notches and bifurcated components in radio profiles of pulsars and magnetars. Evidence for the parallel acceleration maser in pulsar magnetosphere
Dyks, J., Rudak, B., and Rankin, J. M.
2007 , Astronomy and Astrophysics, Volume 465, Issue 3, April III 2007, pp.981-991
Abstract:

Context. Averaged pulse profiles of three nearby pulsars: B1929+10, J0437-4715 and B0950+08 exhibit unusual "double notches". These W-like looking features consist of two adjacent V-shaped dips that approach each other at increasing observation frequency ν_obs roughly at a rate Δ∝ ν_obs-1/2, where Δ is the separation between the notches' minima.

Aims. We show that basic properties of the notches, namely their W-like look and the rate of their converging can be understood within a narrow class of models of coherent radio emission from pulsars: the free electron maser models based on coherent inverse Compton scattering of parallel oscillations of ambient electric field.

Methods. The observed properties of the pulsars imply that the Fourier spectrum of the wiggler-like oscillations is narrow and that the broad-band character of the radio emission reflects the width of the electron energy distribution.

Results. Such a model provides a natural explanation for the frequency-independent separation between the main pulse and interpulse of B0950+08 as well as for the lack of radius to frequency mapping in the conal-like emission of J0437-4715. The frequency behaviour of the main pulse in the profile of the first radio magnetar XTE J1810-197 can also be explained within this model.
Appendices are only available in electronic form at http://www.aanda.org
A Planetary-Mass Companion to the K0 Giant HD 17092
Niedzielski, A., Konacki, M., Wolszczan, A., Nowak, G., Maciejewski, G., Gelino, C. R., Shao, M., Shetrone, M., and Ramsey, L. W.
2007 , The Astrophysical Journal, Volume 669, Issue 2, pp. 1354-1358.
Abstract:
We report the discovery of a substellar-mass companion to the K0 giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360 day periodicity with the standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. As the estimated stellar mass is 2.3 Msolar, the minimum mass of the planet is 4.6 MJ. The planet's orbit is characterized by a mild eccentricity of e=0.17 and a semimajor axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around intermediate-mass stars, and they provide dynamical information on the evolution of planetary systems around post-main-sequence stars.
Infrared OH absorption lines in 1612 MHz OH maser sources
He, J. H., Chen, P. S., Szczerba, R., and Sobolev, A. M.
2007 , Astrophysical Masers and their Environments, Proceedings of the International Astronomical Union, IAU Symposium, Volume 242, p. 320-321
Abstract:
ISO mid-infrared absorption data helps to distinguish between radiative and collisional pumping mechanisms in 1612 MHz OH masers in various environments. Archive data of OH absorption at 34.6 and 53.3μm shows different behavior and different pumping rates for different types of maser sources.
Joint Discussion 2 On the present and future of pulsar astronomy
Becker, W., Gil, J. A., and Rudak, B.
2007 , Highlights of Astronomy, Volume 14, p. 109-138
Abstract:
Neutron stars are formed in supernova explosions. They manifest themselves in many different ways, for example, as pulsars, anomalous X-ray pulsars (AXPs) and soft γ-ray repeaters (SGRs) and the so-called ‘radio-quiet neutron stars’. These objects are made visible by high-energy processes occurring on their surface or in the surrounding region. In most of these objects, ultra-strong magnetic fields are a crucial element in the radio, optical, X-ray and gamma-ray emission processes which dominate the observed spectrum.
Magnetic activity in stellar merger products
Soker, N. and Tylenda, R.
2007 , Monthly Notices of the Royal Astronomical Society, Volume 375, Issue 3, pp. 909-912.
Abstract:
We study the expected X-ray luminosity of stellar merger products several years after merger. The X-ray emission is assumed to result from magnetic activity. The extended envelope of the merger product possesses a large convective region and it is expected to rotate fast. The rotation and convection might give rise to an efficient dynamo operation; therefore we expect strong magnetic activity. Using well-known relations connecting magnetic activity and X-ray luminosity in other types of magnetically active stars, we estimate that the strong X-ray luminosity will start several years after merger, will reach a maximum of Lx ~ 3 × 1030ergs-1, and will slowly decline on a time-scale of ~100 yr. We predict that X-ray emission from V838 Mon which erupted in 2002 will be detected in 2008 with 20 h of observation.
Mixed Chemistry Phenomenon during Late Stages of Stellar Evolution
Szczerba, R., Schmidt, M. R., and Pulecka, M.
2007 , Baltic Astronomy, Vol. 16, p. 134-141
Abstract:
We discuss phenomenon of simultaneous presence of O- and C-based material in the surroundings of evolutionary advanced stars. We concentrate on silicate carbon stars and present observations that directly confirm for them the binary model scenario. We discuss also the class of C-stars with OH emission detected, to which some [WR] planetary nebulae do belong.
Modelling V838 Monocerotis as a Mergeburst Object
Soker, N. and Tylenda, R.
2007 , The Nature of V838 Mon and its Light Echo ASP Conference Series, Vol. 324, Proceedings of the conference held 16-19 May, 2006 in Los Concajos, La Palma, Spain. Edited by Romano, L. M. Corradi and Ulisse Munari. San Francisco: Astronomical Society of the Pacific, 2007., p.280
Abstract:
We discuss the main observational facts on the eruption of V838 Monocerotis in terms of possible outburst mechanisms. We conclude that the stellar merger scenario is the only one which can consistently explain the observations.
New constraints on the mid-IR EBL from the HESS discovery of VHE γ-rays from 1ES 0229+200
Aharonian, F., Akhperjanian, A. G., Barres de Almeida, U., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Bulik, T., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Clapson, A. C., Coignet, G., Cornils, R., Costamante, L., Dalton, M., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubois, F., Dubus, G., Dyks, J., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., 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., Jung, I., Katarzyński, K., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Keogh, D., Komin, N., Kosack, K., Lamanna, G., Latham, I. J., Lemière, A., Lemoine-Goumard, M., Lenain, J.-P., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, D., Maurin, G., McComb, T. J. L., Moderski, R., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Ohm, S., Olive, J.-P., de Oña Wilhelmi, E., Orford, K. J., Osborne, J. L., Ostrowski, M., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Renaud, M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Rudak, B., Ruppel, J., Sahakian, V., Santangelo, A., Schlickeiser, R., Schöck, F., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Stawarz, Ł., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Vivier, M., Völk, H. J., Volpe, F., Wagner, S. J., Ward, M., Zdziarski, A. A., and Zech, A.
2007 , Astronomy and Astrophysics, Volume 475, Issue 2, November IV 2007, pp.L9-L13
Abstract:
Aims:To investigate the very high energy (VHE: >100 GeV) γ-ray emission from the high-frequency peaked BL Lac 1ES 0229+200.

Methods. Observations of 1ES 0229+200 at energies above 580 GeV were performed with the High Energy Stereoscopic System (HESS) in 2005 and 2006.

Results. 1ES 0229+200 is discovered by HESS to be an emitter of VHE photons. A signal is detected at the 6.6σ level in the HESS observations (41.8 h live time). The integral flux above 580 GeV is (9.4±1.5_stat±1.9_syst) × 10-13 cm-2 s-1, corresponding to ~1.8% of the flux observed from the Crab Nebula. The data show no evidence for significant variability on any time scale. The observed spectrum is characterized by a hard power law (Γ = 2.50±0.19_stat±0.10_syst) from 500 GeV to ~15 TeV.

Conclusions. The high-energy range and hardness of the observed spectrum, coupled with the object's relatively large redshift (z = 0.1396), enable the strongest constraints so far on the density of the Extragalactic Background Light (EBL) in the mid-infrared band. Assuming that the emitted spectrum is not harder than Γ_int ≈ 1.5, the HESS data support an EBL spectrum ∝λ-1 and density close to the lower limit from source counts measured by Spitzer, confirming the previous indications from the HEGRA data of 1ES 1426+428 (z=0.129). Irrespective of the EBL models used, the intrinsic spectrum of 1ES 0229+200 is hard, thus locating the high-energy peak of its spectral energy distribution above a few TeV.
Observational Techniques for Detecting Planets in Binary Systems
Muterspaugh, M. W., Konacki, M., Lane, B. F., and Pfahl, E.
2007 , eprint arXiv:0705.3072
Abstract:
Searches for planets in close binary systems explore the degree to which stellar multiplicity inhibits or promotes planet formation. There is a degeneracy between planet formation models when only systems with single stars are studied--several mechanisms appear to be able to produce such a final result. This degeneracy is lifted by searching for planets in binary systems; the resulting detections (or evidence of non-existence) of planets in binaries isolates which models may contribute to how planets form in nature. In this chapter, we consider observational efforts to detect planetary companions to binary stars in two types of hierarchical planet-binary configurations: first ``S-type'' planets which orbit just one of the stars, with the binary period being much longer than the planet's; second, ``P-type'' or circumbinary planets, where the planet simultaneously orbits both stars, and the planetary orbital period is much longer than that of the binary. The S-type planet finding techniques are different for binaries that can or cannot be spatially resolved. For wider systems, techniques reviewed include dualstar interferometric differential astrometry and precision radial velocities. Alternatively, unresolved binaries can be studied using modified dualstar "PHASES-style" differential astrometry or a modification of the radial velocity technique for composite spectra. Should a fortunately aligned--but still long period--binary be found, eclipse timing can also reveal the presence of S-type planets.
Methods. for detecting P-type planets include the composite-spectra variant of the radial velocity technique and eclipse timing.
Observations of V838 Mon and the Nearby Region in the CO J = 1→0, 2→1 and 3→2 Transitions
Kamiński, T., Miller, M., Szczerba, R., and Tylenda, R.
2007 , The Nature of V838 Mon and its Light Echo ASP Conference Series, Vol. 324, Proceedings of the conference held 16-19 May, 2006 in Los Concajos, La Palma, Spain. Edited by Romano, L. M. Corradi and Ulisse Munari. San Francisco: Astronomical Society of the Pacific, 2007., p.103
Abstract:
We present observations of V838 Mon and its close vicinity in the three lowest rotational transitions of CO. The J = 2→1 and 3→2 data were obtained using the 3 m KOSMA telescope. They include on-the-fly maps covering a large area (˜3.4 sq. deg) around V838 Mon and long integrations on the star position. Complementary observations in the CO J = 1→0 transition were obtained using the 13.7 m Delingha telescope. The star position as well as 25 other points preselected in the near vicinity of the object have been measured in this transition.
We report on a detection of two narrow emission components in J = 2→1 and 3→2 transitions at the position of V838 Mon. Lines were found at radial velocities of Vlsr=53.3 km s-1 and Vlsr=-11.0 km s-1. Their origin is unclear. We also briefly discuss results of the observations of the vicinity of V838 Mon.
Observations of V838 Monocerotis in the CO rotational transitions
Kamiński, T., Miller, M., and Tylenda, R.
2007 , Astronomy and Astrophysics, Volume 475, Issue 2, November IV 2007, pp.569-574
Abstract:
Aims:We investigate the structure of a field around the position of V838 Mon as seen in the lowest CO rotational transitions. We also measure and analyse emission in the same lines at the position of V838 Mon.

Methods. Observations have primarily been done in the 12CO J = 2→1 and J = 3→2 lines using the KOSMA telescope. A field of 3.4 squared degrees has been mapped in the on-the-fly mode in these transitions. Longer integration spectra in the on-off mode have been obtained to study the emission at the position of V838 Mon. Selected positions in the field have also been observed in the 12CO J = 1→0 transition using the Delingha telescope.

Results. In the observed field we have identified many molecular clouds. They can be divided into two groups from the point of view of their observed radial velocities. One, having V_LSR in the range 18-32 km s-1, can be identified with the Perseus Galactic arm. The other one, having V_LSR between 44-57 km s-1, probably belongs to the Norma-Cygnus arm. The radial velocity of V838 Mon is within the second range but the object does not seem to be related to any of the observed clouds. We did not find any molecular buble of a 1° dimension around the position of V838 Mon claimed in van Loon et al. An emission has been detected at the position of the object in the 12CO J = 2 →1 and J = 3→2 transitions. The emission is very narrow (FWHM ≃ 1.2 km s-1) and at V_LSR = 53.3 km s-1. Our analysis of the data suggests that the emission is probably extended.
Appendix is only available in electronic form at http://www.aanda.org
On the Present and Future of Pulsar Astronomy
Becker, W., Gil, J., and Rudak, B.
2007 , eprint arXiv:astro-ph/0702254
Abstract:
To face recent observational results obtained in multi-wavelength studies from neutron stars and pulsars with the various theoretical models and to discuss on future perspectives on neutron star astronomy we organized a Joined Discussion (JD02) during the XXVI IAU General Assembly which took place in 2006 August in Prague. More than 150 scientists took actively part in this Joint Discussion. Fourteen invited review talks were presented to view the present and future of pulsar astronomy. Fifty three poster contributions displayed new and exciting results. In this summary we give an overview of the invited review talks and contributed posters. The review talks are subject of review articles which will be published elsewhere. More information on this will be available at http://www.mpe.mpg.de/IAU_JD02 in the near future.
Self-consistent treatment of dynamics and chemistry in the winds from carbon-rich AGB stars. I. Tests of the equilibrium and kinetic chemical codes
Pułecka, M., Schmidt, M. R., Shematovich, V. I., and Szczerba, R.
2007 , Astronomy and Astrophysics, Volume 469, Issue 2, July II 2007, pp.553-560
Abstract:
Aims:The main aim of this paper was to test our (chemical and kinetic) codes, which will be used during self-consistent modelling of dynamics and chemistry in the winds from C-rich AGB stars.

Methods. We used the thermodynamical equilibrium code to test the different databases of dissociation constants. We also calculated the equilibrium content of the gas using the kinetic code that includes the chemical network of neutral-neutral reactions. The influence of reaction rates updated using the UMIST database for Astrochemistry 2005 (UDFA05) was tested.

Results. The local thermodynamical equilibrium calculations show that the NIST database reproduces equilibrium concentrations fairly well in comparison with previous computations, while consistency for the other, commonly used, dissociation constants is worse. The most important finding is that the steady state solution obtained with the kinetic code for the reactions network is different from the thermodynamical equilibrium solution. In particular, the important opacity sources CN and C2 are underabundant relative to thermodynamical equilibrium, while O-bearing molecules (like SiO, H{2}O, and OH) are overabundant. After updating the reaction rates by data from the UDFA05 database, the consistency in O-bearing species becomes much better, however the disagreement in C-bearing species is still present.
Figures 3-5 and 7 are only available in electronic form at http://www.aanda.org
SiO around the Carbon Star IRAS 06238+0904
Pulecka, M., Schmidt, M. R., Szczerba, R., and He, J. H.
2007 , Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes. ASP Conference Series, Vol. 378, proceedings of the conference held 7-11 August 2006 at University Campus, Vienna, Austria. Edited by F. Kerschbaum, C. Charbonnel, and R. F. Wing. San Francisco: Astronomical Society of the Pacific, 2007., p.333
Abstract:
With the IRAM radio telescope we have observed rotational transitions of HCN(1--0), CS(3--2), CS(5--4), and SiO(3--2) in two carbon stars with OH maser emission detected towards them: IRAS 04130+3918 and IRAS 06238 +0904. We present results of modelling the molecular emissions for the latter object. Physical parameters of the envelope were established from a model of the spectral energy distribution. A chemical model was developed for the envelope assuming that it is a genuine carbon star. The observed emissions were fitted with a non-LTE code. We conclude that the observed abundance of the SiO molecule may be explained by the gas-phase chemistry in the envelope.
The Circumstellar Shell of the Post-AGB Star IRAS 22272+5435
Schmidt, M. R., Zacs, L., Pulecka, M., Szczerba, R., and Musaev, F.
2007 , Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes. ASP Conference Series, Vol. 378, proceedings of the conference held 7-11 August 2006 at University Campus, Vienna, Austria. Edited by F. Kerschbaum, C. Charbonnel, and R. F. Wing. San Francisco: Astronomical Society of the Pacific, 2007., p.339
Abstract:
We have analysed optical spectra of the carbon-rich post-AGB star IRAS 22272+5435. The circumstellar components of molecular lines of CN (Red System) and C2 (Phillips and Swan bands) were identified and measured. The mechanism of excitation of the rotational levels of the ground electronic states of CN and C2 was analysed with a non-LTE code. An empirical model accounting for the observed spectral energy distribution was used as the physical model of the shell. An extensive chemical model was constructed based on the elemental abundances obtained from the analysis of optical atomic lines.
The Orbits of the Quadruple Star System 88 Tauri A from PHASES Differential Astrometry and Radial Velocity
Lane, B. F., Muterspaugh, M. W., Fekel, F. C., Williamson, M., Browne, S., Konacki, M., Burke, B. F., Colavita, M. M., Kulkarni, S. R., and Shao, M.
2007 , The Astrophysical Journal, Volume 669, Issue 2, pp. 1209-1219.
Abstract:
We have used high-precision differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) project and radial velocity measurements covering a time span of 20 years to determine the orbital parameters of the 88 Tau A system. 88 Tau is a complex hierarchical multiple system comprising a total of six stars; we have studied the brightest four, consisting of two short-period pairs orbiting each other with an ~18 yr period. We present the first orbital solution for one of the short-period pairs, and determine the masses of the components and distance to the system to the level of a few percent. In addition, our astrometric measurements allow us to make the first determination of the mutual inclinations of the orbits. We find that the subsystems are not coplanar.
Torun catalog of post-AGB and related objects (Szczerba+, 2007)
Szczerba, R., Siódmiak, N., Stasinska, G., and Borkowski, J.
2007 , VizieR On-line Data Catalog: J/A+A/469/799. Originally published in: 2007A&A...469..799S
Abstract:
With the ongoing AKARI infrared sky survey, of much greater sensitivity than IRAS, a wealth of post-AGB objects may be discovered. It is thus time to organize our present knowledge of known post-AGB stars in the galaxy with a view to using it to search for new post-AGB objects among AKARI sources. We searched the literature available on the NASA Astrophysics Data System up to 1 October 2006, and defined criteria for classifying sources into three categories: very likely, possible and disqualified post-AGB objects. The category of very likely post-AGB objects is made up of several classes. We have created an evolutionary, on-line catalogue of Galactic post-AGB objects, to be referred to as the Torun catalogue of Galactic post-AGB and related objects. The present version of the catalogue contains 326 very likely, 107 possible and 64 disqualified objects. For the very likely post-AGB objects, the catalogue gives the available optical and infrared photometry, infrared spectroscopy and spectral types, and links to finding charts and bibliography.
(3 data files).
© Centrum Astronomiczne im. M. Kopernika PAN w Toruniu