The blue-edge problem of the V1093 Her instability strip revisited using evolutionary models with atomic diffusion
S. Bloemen, Haili Hu, C. Aerts, M.A. Dupret, R.H. Østensen, P. Degroote, E. Müller-Ringat, T. Rauch; 2014, Astronomy & Astrophysics, Vol. 569, p. 123
Introduction
The grid of evolutionary subdwarf B star (sdB) models was computed from the start of central He burning, taking into account atomic diffusion due to radiative levitation, gravitational settling, concentration diffusion, and thermal diffusion. We have computed the non-adiabatic pulsation properties of the models and studied the predicted p-mode and g-mode instability strips. The non-adiabatic pulsation properties of all the models in the grid can be downloaded on this webpage. The evolutionary tracks were computed using a code that is an adapted version of the STARS code (Eggleton 1971). The changes made to the code are described in Hu et al. 2008, 2009, 2010 and 2011. The pulsational properties are computed from the evolutionary models using MAD (Dupret et al. 2001).
On this webpage we provide access to the pulsational properties (MAD output) of the models in the grid, as well as basic properties such as effective temperature and radius. The files that contain the structure models (STARS output) are too large to be made available for download here, but can be provided upon request.
For more information, see the accompanying paper (Bloemen et al. 2014).
Use of the models
Anyone is free to use the models made available on this webpage. We kindly ask users to cite Hu et al. 2011 and Bloemen et al. 2014 in any publication for which these models are used.
Data format
The grid is provided in FITS files. Every file contains the information for one evolutionary track, and each extension in the files contains the information on the pulsational properties of one model on such a track. The general header of the file contains information on the track (such as the total mass and the envelope mass of the sdB at the start of the central He burning). The headers per extension provide vital information such as the effective temperature and the surface gravity at the different time steps. The data in the extensions come as a table in which each line represents a pulsation mode. Detailed information on the headers and the data format is given below.
| Keyword | Description |
|---|---|
| Mtot | Total mass of the sdB (solar mass) |
| Menv | Mass of the hydrogen envelope (solar mass) |
| Mcore | Mass of the core, equals total-envelope (solar mass) |
| Z | Metallicity |
| other | Bookkeeping values not relevant to the users of the grid but potentially useful for troubleshooting |
| Keyword | Description |
|---|---|
| Logg | Surface gravity (cgs) |
| Teff | Effective temperature (K) |
| M_M_sun | Mass (solar mass) |
| age_y | Age after ZAEHB (yr) |
| Log_L_L_sun | Luminosity (solar luminosity) |
| R_R_sun | Radius (solar radius) |
| X | Hydrogen fraction |
| Z | Metal fraction |
| Column name | Description |
|---|---|
| l | Spherical degree of the mode |
| n | Radial order (not 100% reliable) |
| freq_cd | Mode frequency (cycles/day) |
| freq_micHz | Mode frequency (microHz) |
| omega_re | Dimensionless non-adiabatic angular frequency |
| omega_re_ad | Dimensionless adiabatic angular frequency |
| omega_im | Dimensionless damping rate (negative = unstable mode) |
| sigma_im_micHz | Damping rate (microHz) |
| f_T | Amplitude of effective temperature variation |
| psi_T | Phase of f_T (degrees) |
| f_g | Amplitude of surface gravity variation |
| psi_g | Phase of f_g (degrees) |
| K | K-value, K=1/omega_re^2 |
| Q_d | Constant of pulsation Q (days): Q=(1/freq_cd)*sqrt((M/Msun)*(R/Rsun)^3) |
| lifetime_d | Mode lifetime (days) |
