Time-dependent models of grain-forming stellar atmospheres

Details Time-dependent models of grain-forming stellar atmospheres Time-dependent models of grain-forming stellar atmospheres

Jun 1982

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1982apj...257..247w&link_type=abstract

Astrophysical Journal, Part 1, vol. 257, June 1, 1982, p. 247-263. Research supported by the Natural Sciences and Engineering R

Astronomy and Astrophysics

Astrophysics

20

Carbon Stars, Radiation Pressure, Stellar Atmospheres, Stellar Envelopes, Stellar Mass Ejection, Stellar Models, Time Dependence, Atmospheric Models, Grain Boundaries, Late Stars, Nucleation, Red Giant Stars, Steady State

Scientific paper

Completely time-dependent models of the expanding atmospheres of cool, carbon-rich stars were calculated. The driving force for the expansion was radiation pressure on grains. The grains were assumed to have the structure of graphite with σ = 1000 ergs cm-2 The stellar parameters adopted for the models were M = 1.5 Msun, L = 1.94 × 104 Lsun, C/H = 1.22 × 10-3, and C/O = 1.76. Two models were generated. Model 1 had T* = 2500 K and model 2, T* = 2400 K. In both models grain nucleation was negligible at supersaturation levels less than 5. At higher supersaturation levels condensation of small (a ≍ 5.5 × 10-8 cm) grains was sufficiently great to generate mass flows. The calculated mass loss rate for model 1 was 6.2 × 10-9 Msun yr-1 and for model 2, 7.4 × 10-8 Msun yr-1. The mass flow approached a steady state in model 1, but in model 2 a small amplitude pulsation was superposed upon the outward flow. Initially this pulsation was very irregular, but after an elapsed time of 27 × 107 s the model had relaxed into a steady pulsation mode with a period of 6.4 × 107 s. This mode was followed for four periods during which the amplitude of the pulses remained constant. The driving force for this pulsation appears to be an opacity-controlled feedback mechanism which operated between the grain-forming region of the model and the hydrogen dissociation zone. In model 1 the opacity of the grains was too small for this mechanism to produce pulsations.

Affiliated with

Also associated with

No associations

Rating

Time-dependent models of grain-forming stellar atmospheres does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Time-dependent models of grain-forming stellar atmospheres, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Time-dependent models of grain-forming stellar atmospheres will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1351570