J/A+A/361/641 Investigation of mass loss mechanism of LPVs (Winters+, 2000)
A systematic investigation of the mass loss mechanism in dust forming
long-period variable stars
Winters J.M., Le Bertre T., Jeong K.S., Helling C., Sedlmayr E.
<Astron. Astrophys. 361, 641 (2000)>
=2000A&A...361..641W 2000A&A...361..641W
ADC_Keywords: Stars, variable ; Mass loss ; Models, atmosphere
Keywords: hydrodynamics - stars: winds, outflows - stars: carbon -
stars: circumstellar matter - stars: mass-loss -
stars: AGB and post-AGB
Abstract:
In order to investigate the relations between the mass loss from
pulsating red giants and quantities which can be obtained from
observations, we have explored the behavior of theoretical models
which treat the time-dependent hydrodynamics of circumstellar
outflows, including a detailed treatment of the dust formation
process. This approach, while ignoring effects such as a possible
non-sphericity of the stellar atmospheres which are difficult to
assess, accounts correctly for factors such as the grain formation and
destruction which are crucial to the mass-loss mechanism. We built a
grid of ∼150 models covering a wide range of physical situations. This
grid allows us to characterize the effects of different parameters,
such as the stellar luminosity and temperature, the period and the
amplitude of the pulsation, and the C/O element abundance ratio, on
the behavior of AGB winds and on the rates of mass loss. We find two
regimes for the stellar outflows.
Description:
Parameters and resultant quantities of a grid of hydrodynamical models
for the circumstellar dust shells around pulsating red giants which
treat the time-dependent hydrodynamics and include a detailed
treatment of the dust formation process.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 86 298 Parameters and resultant quantities of the models
table2.tex 99 925 LaTeX version of table 2
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Model Model name (1)
14- 16 F3.1 solMass M* Stellar mass
18- 21 F4.2 10+4solLum L* Stellar luminosity
23- 26 I4 K T* Stellar temperature
28- 31 F4.2 --- C/O Carbon-to-oxygen ratio
33- 36 I4 d P Pulsation period
38- 40 F3.1 km/s Dvp Pulsation amplitude
42- 49 E8.1 solMass/yr <dM/dt> ? Average mass loss rate
51- 55 F5.2 --- e_<dM/dt> ? Relative standard deviation of dM/dt
57- 60 F4.1 km/s <v{inf}> ? Average outflow velocity
62- 64 F3.1 10-3 Dust/Gas ? Average dust-to-gas mass ratio
66- 69 F4.2 --- K-L' ? Average K-L' color index
71- 86 A16 --- Type Type of model (2)
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Note (1): the footnote symbols are:
0: Maron (1990Ap&SS.172...21M 1990Ap&SS.172...21M)
x: AC1, Rouleau & Martin (1991ApJ...377..526R 1991ApJ...377..526R)
D: Edoh (1983, Ph. D. Thesis, University of Arizona, (E))
Note (2): Model type (Sect. 3.1):
A: Models with <α>t>1, dM/dt<3*10-7M☉/yr
AB: Models with <α>t<1, dM/dt>10-6M☉/yr
B: Models with <α>t=1, dM/dt<3*10-7M☉/yr
"static state": The mass loss of these models is decreasing steadily with time
and the velocity is approaching zero, i.e. the circumstellar
shell is approaching a static state after a transition phase,
where material is falling back to the star.
no wind: Models that do not develop a wind structure
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Acknowledgements: Jan Martin Winters
(End) Patricia Bauer [CDS] 29-Sep-2000