VLA observations of class I methanol masers in the region of low-mass star formation L1157 |
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| Authors: | S V Kalenskii S Kurtz V I Slysh P Hofner C M Walmsley L E B Johansson P Bergman |
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| Institution: | 1.Astro Space Center,Lebedev Physical Institute,Moscow,Russia;2.Centro de Radioastronomia y Astrofizika,Universidad Nacional Autonoma de Mexico,Mexico,Mexico;3.Physics Department,New Mexico Institute of Technology,Socorro,USA;4.National Radio Astronomy Observatory,Socorro,USA;5.Max-Planck-Institut für Radioastronomie,Bonn,Germany;6.Osservatorio Astrofisico di Arcetri,Florence,Italy;7.Onsala Space Observatory,Onsala,Sweden |
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| Abstract: | We present the results of VLA observations of a maser candidate in the low-mass star formation region L1157 in the 70-61
A
+ transition at 44 GHz. The line is emitted by a compact, undoubtedly maser source associated with clump B0a, which is seen
in maps of L1157 in thermal lines of methanol and other molecules. A much weaker compact source is associated with clump B1a,
which is brighter than B0a in thermal methanol lines. The newly detected masers may form in thin layers of turbulent post-shock
gas. In this case, the maser emission may be beamed, so that only an observer located in or near the planes of the layers
can observe strong masers. On the other hand, the maser lines are double with a “red” asymmetry, indicating that the masers
may form in collapsing clumps. A detailed analysis of collapsing-cloud maser models and their applicability to the masers
in L1157 will be developed in subsequent papers. |
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