Results 141 to 150 of about 1,279 (175)

On radiative pumping of interstellar methanol masers

Chinese Astronomy and Astrophysics, 1997
Abstract From the observed data of 17 Class-II methanol masers and their asociated HII regions and infrared sources and using the maser photon emission rate and the brightness temperature as two constraints on the pump, we conclude that infrared sources with a brightness temperature of about 100 K and a photon rate of about 10 53 s −1 , associated ...
Xing-wu Zheng, Zhao-fen Ling
exaly   +3 more sources

Modelling interstellar water masers

Astrophysics and Space Science, 1995
Radiative transfer calculations for interstellar H2O have been performed using accelerated A-iteration (ALI) techniques. The results show strong maser action from known maser transitions, as well as predicting new strong maser transitions for ν > 1.5 THz. © 1995 Kluwer Academic Publishers.
Yates, JA, Gray, MD, Field, D
openaire   +3 more sources

A Class of Interstellar OH Masers Associated with Protostellar Outflows [PDF]

Astrophysical Journal, 2003
Using the Very Large Array, we have detected weak OH maser emission near the Turner-Welch protostellar source in the W3 OH region. Unlike typical interstellar OH masers, which are associated with ultracompact H II regions, our measured positions and ...
M J Reid, K M Menten
exaly   +3 more sources

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Interstellar hydroxyl and water masers and formaldehyde masers and dasars

Reports on Progress in Physics, 1974
A review of the observational data on anomalous emission by OH, H2O and H2CO molecules and on anomalous absorption by H2CO molecules. Various theories advanced to account for these data and some models of a few particular sources are discussed.
D ter Haar, M A Pelling
exaly   +2 more sources

Possible new interstellar masers

Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 1980
Abstract A collisional mechanism for the production of population inversion in the Λ-doublet sub-levels of the lowest rotational energy levels of diatomic molecules is considered. This leads to the conclusion that not only should the known celestial masers, OH and CH, be capable of exhibiting stimulated emission, but also H F+, HC1 ...
Elizabeth Gold, R. E. Hammersley, W. G. Richards   +2 more
openaire   +2 more sources

Radiative Stability of the Interstellar Masers

Publications of the Astronomical Society of Japan, 1974
Abstract The stability of the radiation field in the interstellar masers is studied using the radiative transfer equations and the rate equations. The model used is the cylindrical homogeneous maser with steady pumping. It is found that the maser whose optical depth is larger than a critical value is unstable and has no stable steady ...
S. Deguchi
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Radiative stability of interstellar masers ? A variational technique

Astrophysics and Space Science, 1982
A variational technique has been developed to study the stability of the radiation field in a cylindrical homogeneous interstellar maser with steady state pumping. A dynamical potential has been constructed, the extremal of which gives the radiative transfer equations and rate equations.
K. Sen
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Ammonia masers in the interstellar medium

, 1993
Since 1986, 10 ammonia masers have been found. Most of these are found in the sources W51D, W51e1/e2, NGC7538, DR21 and W33. Among them are a few masers or maser candidates, arising from metastable inversion lines. There are many more masers arising from non-metastable inversion lines. The most outstanding is intense maser emission from the (J,K)=(9,6)
T. L. Wilson, P. Schilke
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Interstellar Masers and Star Formation in the Galaxy

1988
Interstellar molecular lines have produced spectacular examples of non-equilibrium excitation, culminating in strong maser action of OH,SiO,H2O and CH3OH. Within the past 10 years it was recognized that maser emission is associated with star formation.
G. Winnewisser
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A shock origin for interstellar H2O masers

, 1993
We present a comprehensive model for the powerful H2O masers observed in starforming regions. In this model the masers occur behind dissociative shocks propagating in dense regions (preshock density n o ≈ 106 – 108 cm−3). This paper focuses on high-velocity (ν s ≳ 30 km/s) dissociative shocks in which the heat of H2 reformation on dust grains maintains
David Hollenbach, Moshe Elitzur, Christopher F. McKee   +2 more
openaire   +2 more sources