Spectra of Plages on the Sun and Stars. II. The H i H alpha Line
Abstract
Spectra of solar plages are used to define indices of plage emission properties in the region of the H I Hα line. Results include the following: (I) The range of Hα emission in solar plages matches the range observed in solar-type stars. (2) Emission in the wings of Hα causes a systematic error in stellar temperature measurements. (3) Plage emission at disk center is dominated by photospheric radiation, not chromospheric. (4) Integrated over the visible spectrum, the emission from a plage is constant to within a factor of 2 as it transits the disk. (5) A second parameter in addition to the average magnetic field strength is needed to specify the plage atmosphere. (6) The width and shift of the chromospheric core of the Hα line are nonlinearly proportional to plage strength and can be used to infer the area coverage of plage on an unresolved system like a star.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- September 1986
- DOI:
- 10.1086/191138
- Bibcode:
- 1986ApJS...62..241L
- Keywords:
-
- SUN: CHROMOSPHERE;
- SUN: PLAGES;
- SUN: SPECTRA