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Maser and thermal methanol emission in the millimeter wave range: new masers at 1.3 mm and 2.8 mm

Published online by Cambridge University Press:  03 August 2017

Sergei V. Kalenskii ,
Vyacheslav I. Slysh  and
Irina E. Val'tts
Sergei V. Kalenskii
Affiliation:
Astro Space Center, Lebedev's Physical Institute, Profsoyuznaya str. 84/32, 117810 Moscow, Russia
Vyacheslav I. Slysh
Affiliation:
Astro Space Center, Lebedev's Physical Institute, Profsoyuznaya str. 84/32, 117810 Moscow, Russia
Irina E. Val'tts
Affiliation:
Astro Space Center, Lebedev's Physical Institute, Profsoyuznaya str. 84/32, 117810 Moscow, Russia

Abstract

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Results of a survey of Galactic star-forming regions in the lines of methanol 8−1 − 70E at 229.8 GHz, 3−2 − 4−1E at 230.0 GHz, 00 − 1−1E at 108.9 GHz, and a series of methanol lines J1 − J0E near 165 GHz are presented. Two masers, DR 21 (OH) and DR 21 West, and two maser candidates, L 379 IRS3 and NGC 6334I(N), as well as 16 thermal sources are found at 229.8 GHz. This is the first detection of methanol masers at a wavelength as short as 1 mm. At 108.9 GHz, masers were found towards G345.01 + 1.79 and probably, towards M 8E. Thermal emission is found towards 28 objects. Only thermal emission was found at 165 and 230.0 GHz (20 and 7 sources, respectively). The masers at 229.8 GHz belong to class I, whereas those at 108.9 GHz belong to class II, according to the classification by Menten (1991). The masers in DR 21 (OH) and DR 21 West can be roughly fitted by models with the gas kinetic temperature of the order of 50 K. The detection of the 108.9 GHz masers towards G345.01 + 1.79 and M 8E may indicate on a specific geometry of these objects. The combination of the existence of the class II J0 - J−1E masers towards W 3(OH), G345.01 + 1.79, W 48, and Cep A and our non-detection of the 3−2 − 4−1E and J1 - J0E lines is an evidence that the class II masers in these objects are pumped by the radiation of hot dust rather than by that of UC HII-regions.

Type
Part 1. Star Formation
Information
Symposium - International Astronomical Union , Volume 206: Cosmic Masers: From Protostars to Blackholes , 2002 , pp. 191 - 194
Copyright
Copyright © Astronomical Society of the Pacific 2002 

References

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