Stellar granulation. III. Hydrodynamic model atmospheres.
Abstract
Detailed models for the three-dimensional, time-dependent and radiation-coupled hydrodynamics of solar granular convection have been adapted to stellar conditions, and extensive numerical simulations have been carried out to model four different stars in the vicinity of the sun in the H-R diagram. The results from the simulations, showing the three-dimensional structure and time evolution of temperature, velocity, and pressure features in stellar photospheres, are presented. They are then used as sets of temporally and spatially varying model atmospheres in which radiative transfer computations are made of the continuum and line radiation leaving the stars. Synthetic images show the optical appearance of stellar surface structure at different positions across stellar disks. Synthetic spectral line profiles are computed for different locations and times, and the buildup of average line profiles is examined for lines of different strength, excitation potential, ionization level, and wavelength region. The average line profiles are then used as an input to synthesize the disk-integrated flux of photospheric Fe lines for stars of different rotational velocities in order to predict observable spectral line shapes, asymmetries, and wavelength shifts.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1990
- Bibcode:
- 1990A&A...228..155N
- Keywords:
-
- Astronomical Models;
- Hydrodynamics;
- Late Stars;
- Solar Granulation;
- Stellar Atmospheres;
- F Stars;
- G Stars;
- Radiative Transfer;
- Stellar Magnetic Fields;
- Stellar Temperature;
- Subgiant Stars;
- Astrophysics