Hostname: page-component-7479d7b7d-8zxtt Total loading time: 0 Render date: 2024-07-11T19:44:00.373Z Has data issue: false hasContentIssue false
  • English
  • Français

Pumping of Strong H2O Cosmic Masers

Published online by Cambridge University Press:  14 August 2015

V. S. Strelnitsky
V. S. Strelnitsky*
Affiliation:
Astronomical Council, USSR Academy of Sciences

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

All the existing models of H2O masers fail to explain such a strong source as W49 N. Observed and theoretical quantities are related by: nH2OWPℓ3 ≳ 1046 S, where S is the maser flux density (in Janskys), nH2O is the H2O number density (cm−3), Wp is pump rate (s−1), and ℓ is the length of amplification region on the line of sight (cm). Models involving vibrational activation (or deactivation) of H2O by H2 (Goldreich and Kwan, 1974; Norman and Silk, 1979), with the usual cross-section σν ≲ 10−19cm2, require ℓ > 1016 cm for the strongest H2O features (∼104 Jy), which is unacceptable in view of the VLBI results. Besides, because σν is so small, it is questionable if vibrational pumping could control rotational level populations at all. Depending on the energy source and sink there are four possible schemes of rotational pumping: CR, RC, RR, and CC (C - collisional, R - radiative). The first was modelled by de Jong (1973) and by Shmeld et al. (1976). Though difficulties with the sink (Goldreich and Kwan, 1974; 1979) are avoidable in the model by Shmeld et al. (Strelnitsky, 1979), ℓ ≳ 1015 − 1016 cm is still required for the strongest features. Therefore other possibilities of rotational pumping are being investigated. One CC-model is presented below.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 87: Interstellar Molecules , 1980 , pp. 591 - 592
Copyright
Copyright © Reidel 1980 

References

Bolgova, G.T.: 1979, submitted to Nauchn. Inf. Astron. Council.Google Scholar
Goldreich, P., and Kwan, J.: 1974, Astrophys. J. 191, pp. 93-100.Google Scholar
Goldreich, P., and Kwan, J.: 1979, Astrophys. J. 227, pp. 150-151.CrossRefGoogle Scholar
Gammon, R.H.: 1976, Astron. Astrophys. 50, pp. 297-313.Google Scholar
Itikawa, I.: 1972, J. Phys. Soc. Japan 32, pp. 217-226.CrossRefGoogle Scholar
de Jong, T.: 1973, Astron. Astrophys. 26, pp. 297-313.Google Scholar
Norman, C., and Silk, J.: 1979, Astrophys. J. 228, pp. 197-205.Google Scholar
Perri, F., and Cameron, A.G.W.: 1974, Icarus 22, pp. 416-425.CrossRefGoogle Scholar
Shmeld, I.K., Strelnitsky, V.S., and Muzylev, V.V.: 1976, Astron. Zh. 53, pp. 728-741.Google Scholar
Strelnitsky, V.S.: 1979, submitted to Astron. Zh.Google Scholar
Strelnitsky, V.S., and Sunjaev, R.A.: 1972, Astron. Zh. 49, p. 704.Google Scholar
White, C.J.: 1979, Mon. Not. Roy. Astron. Soc. 186, pp. 377-381.Google Scholar