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| 2. |
- Kalenskii, S.V., et al.
(författare)
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Class I methanol masers in low-mass star formation regions
- 2012
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Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 161-165
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Konferensbidrag (refereegranskat)abstract
- Four Class I maser sources were detected at 44, 84, and 95 GHz toward chemically rich outflows in the regions of low-mass star formation NGC 1333I4A, NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a similar outflow, NGC 2023. Flux densities of the newly detected masers are no more than 18 Jy, being much lower than those of strong masers in regions of high-mass star formation. The brightness temperatures of the strongest peaks in NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of the peak in NGC 1333I2A is only 176 K. However, a rotational diagram analysis showed that the latter source is also a maser. The main properties of the newly detected masers are similar to those of Class I methanol masers in regions of massive star formation. The former masers are likely to be an extension of the latter maser population toward low luminosities of both the masers and the corresponding YSOs.
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| 3. |
- Kalenskii, S.V., et al.
(författare)
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Class I methanol masers in regions of low-mass star formation
- 2007
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Ingår i: Proceedings of "Millimeter wave astronomy and star formation", ed. I. Zinchenko, Nizhny Novgorod, Russia, August 2007, Inst. of Applied Physics RAS. ; , s. 10-14
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Kalenskii, S. V., et al.
(författare)
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Search for Class I methanol masers in low-mass star formation regions
- 2010
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 405:1, s. 613-620
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Tidskriftsartikel (refereegranskat)abstract
- A survey of young bipolar outflows in regions of low-to-intermediate-mass star formation has been carried out in two Class I methanol maser transitions: 7(0) - 6(1)A+ at 44 GHz and 4(-1) - 3(0)E at 36 GHz. We detected narrow features towards NGC 1333I2A, NGC 1333I4A, HH25MMS and L1157 at 44 GHz, and towards NGC 2023 at 36 GHz. Flux densities of the lines detected at 44 GHz are no higher than 11 Jy and the relevant source luminosities are about 1022 erg s-1, which is much lower than those of strong masers in high-mass star formation regions. No emission was found towards 39 outflows. All masers detected at 44 GHz are located in clouds with methanol column densities of the order of or larger than a few x1014 cm-2. The upper limits for the non-detections are typically of the order of 3-5 Jy. Observations in 2004, 2006 and 2008 did not reveal any significant variability of the 44 GHz masers in NGC 1333I4A, HH25MMS and L1157.
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| 8. |
- Kalenskii, S. V., et al.
(författare)
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VLA Observations of Class I Methanol Masers in the Region of Low-Mass Star Formation L1157
- 2010
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Ingår i: Astronomy Reports. - 1562-6881 .- 1063-7729. ; 54:10, s. 932-939
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of VLA observations of a maser candidate in the low-mass star formation region L1157 in the 7(0)-6(1) 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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