X-rays and HZ Herculis
Abstract
A detailed calculation of the structural and radiant characteristics of the X-ray-illuminated atmosphere of HZ Her is necessary before it is possible to substract its contribution from the total light and study the more subtle effects of nonuniform illumination and contributions from other system components. It is shown that an X-ray-irradiated atmosphere can be divided into four distinct zones. In order of decreasing height, these zones are a nearly isothermal photosphere strongly coupled to its own thermal radiation with additional heating by hard X-ray photoionization and Compton scattering, and two sharp transitions to a high-temperature corona in equilibrium with the X-rays. The corona becomes gravitationally unbound a short distance (compared to the binary separation) above the transition and expands into a stellar wind. Both the lines and continuum observations, when compared with emergent radiation calculations, are consistent with an incident spectrum containing as much flux below hv = 1 keV as above hv = 1 keV.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1981
- DOI:
- 10.1086/158735
- Bibcode:
- 1981ApJ...244..555A
- Keywords:
-
- Eclipsing Binary Stars;
- Stellar Atmospheres;
- Stellar Radiation;
- X Ray Sources;
- Atmospheric Heating;
- Atmospheric Models;
- Hydrodynamic Equations;
- Line Spectra;
- Stellar Coronas;
- Thermal Radiation;
- Variable Stars;
- Astronomy