Database of molecular masers and variable stars

We present the database of maser sources in H2 O, OH and Si O lines that can be used to identify and study variable stars at evolved stages. Detecting the maser emission in H2 O, OH and Si O molecules toward infrared-excess objects is one of the methods for identifing long-period variables(LPVs, including miras and semiregulars), because these stars exhibit maser activity in their circumstellar shells. Our sample contains 1803 known LPV objects. Forty-six percent of these stars(832 objects) manifest maser emission in the line of at least one molecule: H2 O, OH or Si O. We use the database of circumstellar masers in order to search for LPVs which are not included in the General Catalogue of Variable Stars(GCVS). Our database contains 4806 objects(3866 objects without associations in GCVS) with maser detection in at least one molecule. Therefore it is possible to use the database in order to locate and study the large sample of LPV stars. The database can be accessed at http://maserdb.net.     

On Some Issues of Cross-Identification of Astronomical Catalogs

Astronomy Reports - The paper deals with the issues of cross-identification of sources from various astronomical catalogs. One of the main problems under consideration is how to cross-identify a...     

Molecular emission in dense massive clumps from the star-forming regions S231–S235

The paper is concerned with the study of the star-forming regions S231–S235 in radio lines of molecules of the interstellar medium—carbon monoxide (CO), ammonia (NH₃), cyanoacetylene (HC₃N), in maser lines—methanol (CH₃OH) and water vapor (H₂O). The regions S231–S235 belong to the giant molecular cloudG174+2.5. The goal of this paper is to search for new sources of emission toward molecular clumps and to estimate their physical parameters from CO and NH₃ molecular lines. We obtained new detections ofNH₃ andHC₃Nlines in the sources WB89673 and WB89 668 which indicates the presence of high-density gas. From the CO line, we derived sizes, column densities, and masses of molecular clumps. From the NH₃ line, we derived gas kinetic temperatures and number densities in molecular clumps. We determined that kinetic temperatures and number densities of molecular gas are within the limits 16–30 K and 2.8–7.2 × 10³ cm^?3 respectively. The shock-tracing line of CH₃OH molecule at a frequency of 36.2 GHz was detected in WB89 673 for the first time.     

Study of the filamentary infrared dark cloud G192.76+00.10 in the S254–S258 OB complex

We present results of a high resolution study of the filamentary infrared dark cloud G192.76+00.10 in the S254-S258 OB complex in several molecular species tracing different physical conditions. These include three isotopologues of carbon monoxide(CO), ammonia(NH3) and carbon monosulfide(CS). The aim of this work is to study the general structure and kinematics of the filamentary cloud, and its fragmentation and physical parameters. The gas temperature is derived from the NH3(J, K) =(1,1),(2, 2) and ~(12)CO(2-1) lines, and the ~(13)CO(1-0), ~(13)CO(2-1) emission is used to investigate the overall gas distribution and kinematics. Several dense clumps are identified from the CS(2-1)data. Values of the gas temperature lie in the range 10-35 K, and column density N(H2) reaches the value 5.1 x 10~(22) cm~(-2). The width of the filament is of order 1 pc. The masses of the dense clumps range from ～ 30 M_☉ to ～ 160 M_☉. They appear to be gravitationally unstable. The molecular emission shows a gas dynamical coherence along the filament. The velocity pattern may indicate longitudinal collapse.