Models of circumstellar molecular radio line emission
نویسندگان
چکیده
منابع مشابه
Models of circumstellar molecular radio line emission
Using a detailed radiative transfer analysis, combined with an energy balance equation for the gas, we have performed extensive modelling of circumstellar CO radio line emission from a large sample of optically bright carbon stars, originally observed by Olofsson et al. (ApJS, 87, 267). Some new observational results are presented here. We determine some of the basic parameters that characteriz...
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We present a list of post-AGB stars showing molecular line absorption and emission in the optical spectrum. Two objects show CH, one in emission and one in absorption, and ten stars show C2 and CN in absorption. The Doppler velocities of the C2 lines and the rotational temperatures indicate that the line forming region is the AGB remnant. An analysis of the post-AGB stars of which CO millimeter...
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Aims. The main aim is to derive reliable mass-loss rates and circumstellar SiO abundances for a sample of 40 S-type AGB stars based on new multi-transitional CO and SiO radio line observations. In addition, the results are compared to previous results for M-type AGB stars and carbon stars to look for trends with chemical type. Methods. The circumstellar envelopes are assumed to be spherically s...
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We demonstrate the efficiency of high quality optical spectroscopic observations of two compact radio sources, PKS 1549-79 and PKS 1345+12, as a probe of the kinematics and physical conditions in the circumnuclear gas in the early stages of radio source evolution. We outline a schematic model for PKS 1345+12 based on the model for PKS 1549-79 proposed by Tadhunter et al. (2001) in which the you...
متن کاملLine emission from circumstellar disks around A stars
The nature of the tenuous disks around A stars has raised considerable controversy in the literature during the past decade. The debate whether or not the disk around β Pictoris contains gaseous molecular hydrogen is only the most recent example. Since CO is in general a poor tracer for the gas content of these low mass disks, we discuss here detailed emission line calculations for alternative ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2001
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20010072