Issue |
A&A
Volume 438, Number 1, July IV 2005
|
|
---|---|---|
Page(s) | 273 - 289 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20042555 | |
Published online | 06 July 2005 |
An empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich Asymptotic Giant Branch stars
1
Astrophysics Group, School of Physical & Geographical Sciences, Keele University, Staffordshire ST5 5BG, UK e-mail: jacco@astro.keele.ac.uk
2
European Southern Observatory, Karl-Schwarzschild Straße 2, 85748 Garching bei München, Germany
3
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
4
School of Physics and Astronomy, University of Manchester, Sackville Street, PO Box 88, Manchester M60 1QD, UK
5
Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
Received:
16
December
2004
Accepted:
12
April
2005
We present an empirical determination of the mass-loss rate as a function of
stellar luminosity and effective temperature, for oxygen-rich dust-enshrouded
Asymptotic Giant Branch stars and red supergiants. To this aim we obtained
optical spectra of a sample of dust-enshrouded red giants in the Large
Magellanic Cloud, which we complemented with spectroscopic and infrared
photometric data from the literature. Two of these turned out to be hot
emission-line stars, of which one is a definite B[e] star. The mass-loss rates
were measured through modelling of the spectral energy distributions. We thus
obtain the mass-loss rate formula , valid
for dust-enshrouded red supergiants and oxygen-rich AGB stars. Despite the low
metallicity of the LMC, both AGB stars and red supergiants are found at late
spectral types. A comparison with galactic AGB stars and red supergiants shows
excellent agreement between the mass-loss rate as predicted by our formula and
that derived from the 60 μm flux density for dust-enshrouded objects, but
not for optically bright objects. We discuss the possible implications of this
for the mass-loss mechanism.
Key words: stars: AGB and post-AGB / stars: carbon / stars: mass-loss / supergiants / Magellanic Clouds / infrared: stars
© ESO, 2005
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