ASPHERICAL DUST ENVELOPES AROUND OXYGEN-RICH AGB STARS
نویسندگان
چکیده
منابع مشابه
Mass loss and dust formation around oxygen - rich evolved stars
Infrared spectra of a number of evolved O-rich stars have been obtained with the Short and Long Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4–197μm) obtained by combining observations made with the two spectrometers includes practically all of the flux emitted by the sources, and allows us to determine the emission and absorption featu...
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Aims. Given their photospheric origin and refractive nature, SiS molecules can provide important constraints on the relative roles of dust condensation and non-equilibrium processes in regulating the chemistry in circumstellar envelopes around evolved stars. Methods. New SiS multi-transition (sub-)millimetre line observations of a sample of AGB stars with varying photospheric C/Oratios and mass...
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Dust is formed in the expanding atmosphere during late stages of stellar evolution. Dust influences the dynamics and thermodynamics of the stellar atmosphere by its opacity. The dust opacity depends both on the optical properties of the grain material as well as on the amount of dust present. A rich source of information on some mineral phases of dust in AGB stars comes from the study of presol...
متن کاملA cold detached dust envelope around an oxygen-rich Mira-type AGB star R Hydrae
The circumstellar structure of R Hydrae has been investigated in the IRAS survey scan data. R Hya is a late Mtype Mira variable star whose IRAS LRS spectrum is classified as 15 (no feature). But, it shows a remarkable infrared excess in the IRAS photometric data, which cannot be explained by an oxygen-rich circumstellar dust envelope of a mass losing latetype star without showing a significant ...
متن کاملToo little radiation pressure on dust in the winds of oxygen-rich AGB stars
Aims. It is commonly assumed that the massive winds of AGB stars are dust-driven and pulsation-enhanced. However, detailed frequency-dependent dynamical models which can explain the observed magnitudes of mass loss rates and outflow velocities have been published so far only for C-stars. This letter reports on first results of similar models for oxygen-rich AGB stars. The aim is to provide a be...
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ژورنال
عنوان ژورنال: Journal of Astronomy and Space Sciences
سال: 2006
ISSN: 2093-5587
DOI: 10.5140/jass.2006.23.4.303