Results 141 to 150 of about 4,855 (170)

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 ...
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Masers, Lasers and the Interstellar Medium

Astrophysics and Space Science, 1997
This paper discusses recent results obtained by myself and my colleagues in three domains of astrophysics: interstellar supersonic turbulence, circumstellar disks, and natural masers and lasers. S.A. Kaplan, S.B. Pikelner, and I.S. Shklovskii were among those who, 30-40 years ago, laid the foundation of these domains.
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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
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Magnetic fields in interstellar water masers

2008
We report the first detection of Zeeman splitting in the (616−523) rotational transition of interstellar H2O masers. The measurements of Stokes parameter V and I spectra (circular polarization) have been performed at the MPIfR 100-m telescope. Depending on the hyperfine transition that is actually masing, we derive typical magnetic field strengths of B‖
D. Fiebig, R. Güsten
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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
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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 scattering of maser radiation

1993
Interstellax scattering of pulsars, extragalactic sources, and galactic masers is used to discuss the overall galactic distribution of scattering material and the implied angular scattering vs galactic coordinates. I discuss the prospects for observing diffractive and refractive scintillations of maser signals.
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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.
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Recent Results in Astronomy III: Interstellar Masers

1989
This lecture is aimed at reviewing some of the recent results arising from VLBI observations of Galactic objects. Bryan Anderson has discussed stellar VLBI, pulsar observations and the spectacular VLBI data obtained on objects such as SS433. I shall concentrate on molecular masers, the Galactic Centre and the study of the interstellar medium. I make no
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Angular structure and motions of interstellar masers

2008
A brief historical account is given of the discovery of OH emission and the experiments that led to the identification of the radiation mechanism as maser amplification. An outline is presented of the progress by the MIT, CfA and Jodrell Bank groups in mapping the prototypical maser, W3(OH).
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