Title: Mass-losing Semiregular Variable Stars in Baade's Windows
Authors: Alard, C ×
Blommaert, Joris
Cesarsky, C
Epchtein, N
Felli, M
Fouque, P
Ganesh, S
Genzel, R
Gilmore, G
Glass, IS
Habing, H
Omont, A
Perault, M
Price, S
Robin, A
Schultheis, M
Simon, G
van Loon, JT
Alcock, C
Allsman, RA
Alves, DR
Axelrod, TS
Becker, AC
Bennett, DP
Cook, KH
Drake, AJ
Freeman, KC
Geha, M
Griest, K
Lehner, MJ
Marshall, SL
Minniti, D
Nelson, C
Peterson, BA
Popowski, P
Pratt, MR
Quinn, PJ
Sutherland, W
Tomaney, AB
Vandehei, T
Welch, DL #
Issue Date: May-2001
Publisher: University of Chicago Press for the American Astronomical Society
Series Title: Astrophysical Journal vol:552 pages:289-308
Abstract: By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 μm) and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galactic bulge. These stars are mainly giants of late M spectral type, evolving along the asymptotic giant branch (AGB). They are found to possess a wide and continuous distribution of pulsation periods and to obey an approximate logP-M<SUB>bol</SUB> relation or set of such relations. Approximate mass-loss rates M&d2; in the range of ~1Î10<SUP>-8</SUP> to 5Î10<SUP>-7</SUP> M<SUB>solar</SUB> yr<SUP>-1</SUP> are derived from ISOGAL mid-infrared photometry and models of stellar spectra adjusted for the presence of optically thin circumstellar silicate dust. Mass-loss rates depend on luminosity and pulsation period. Some stars lose mass as rapidly as short-period Mira variables but do not show Mira-like amplitudes. A period of 70 days or longer is a necessary but not sufficient condition for mass loss to occur. For AGB stars in the mass-loss ranges that we observe, the functional dependence of mass-loss rate on temperature and luminosity can be expressed as M&d2;~T<SUP>α</SUP>L<SUP>β</SUP>, where α=-8.80<SUP>+0.96</SUP><SUB>-0.24</SUB> and β=+1.74<SUP>+0.16</SUP><SUB>-0.24</SUB>, in agreement with recent theoretical predictions. If we include our mass-loss rates with a sample of extreme mass-losing AGB stars in the Large Magellanic Cloud and ignore T as a variable, we get the general result for AGB stars that M&d2;~L<SUP>2.7</SUP>, valid for AGB stars with 10<SUP>-8</SUP><M&d2;<10<SUP>-4</SUP> M<SUB>solar</SUB> yr<SUP>-1</SUP>
ISSN: 0004-637X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Non-KU Leuven Association publications
× corresponding author
# (joint) last author

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