Results 121 to 130 of about 423 (145)
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Spatial and velocity structure of circumstellar water masers
New Astronomy Reviews, 1999We discuss the results of our study of water masers at 22 GHz with the Very Large Array. We conclude, from the anticorrelation between the intensity and linewidth of the maser features, that they are unsaturated; turbulence must exist in order to explain the large observed opacities.
F Colomer
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The Circumstellar Environment of Evolved Stars as Revealed by Studies of Circumstellar Water Masers
Publications of the Astronomical Society of the Pacific, 1997exaly +2 more sources
Searches for OH masers in the circumstellar envelopes of red giant irregular variable stars
Monthly Notices of the Royal Astronomical Society, 2004 International audienceIrregular variables of type Lb share many characteristics with asymptotic giant branch (AGB) stars such as Miras and semiregulars (SRs). Despite their large number, irregulars are poorly understood.
Sivagnanam, Philippe
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Models of Circumstellar Masers
1998Abstract Maser emission involving SiO, H2O and OH has been observed in the direction of a large number of AGB stars. These stars have the characteristic that they lose mass with rates between 10-8 solar masses per year to as much as 10.,..4 solar masses per year.
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1993
The circumstellar envelopes of a sample red giants and supergiants have been investigated using MERLIN 22GHz H2O maser observations and single dish observations of the 22, 321, and 325GFfz water maser lines. The MERLIN data shows that inner circumstellar envelopes are generally asymmetrical with evidence for discs and bipolar outflows among the ...
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The circumstellar envelopes of a sample red giants and supergiants have been investigated using MERLIN 22GHz H2O maser observations and single dish observations of the 22, 321, and 325GFfz water maser lines. The MERLIN data shows that inner circumstellar envelopes are generally asymmetrical with evidence for discs and bipolar outflows among the ...
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Amplification of stellar background by circumstellar masers
Astrophysics and Space Science, 1988The calculations with the use of simple maser model show that the stellar background contributes negligibly to the mean peak intensities at 1612 MHz. Under some conditions, however, the contribution from the central star may constitute a few percent of the mean peak intensity.
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Circumstellar Masers in the Galactic Center
2003Blind and targeted surveys for maser emission (OH, H2O, and SiO) in the central degree (≤ 150 pc) of the Galactic center will be discussed, with the emphasis on masers in OH/IR stars. Using the masers, some recent clues about the kinematics and evolution of the central part of the Milky Way galaxy will be given.
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FG3: Spatial and frequency modeling of circumstellar masers
Vistas in Astronomy, 1997Abstract We have developed a computer program (called “FG3”) that is useful to model images of spectral line emission. We have applied it successfully to the study of maser emission in the circumstellar envelopes of late-type stars. The program will search for maser sources, blended spatially and in frequency, and fit 3D Gaussians to them.
F. Colomer, K.M. Menten, M.J. Reid
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Optical pumping of circumstellar SiO masers
1995We investigate the influence of the photospheric line spectrum on the optical pumping of circumstellar CO. As pump radiation we consider in particular the photospheric spectrum of a cool carbon star (T eff =2600 K). This spectrum shows deep absorption lines in the wavelength range of the pump lines (4.6 μ). Of particular importance for the pump process
E. Rausch, W. H. Kegel, T. Tsuji
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