Hydrogen self-absorption in the solar chromosphere.
Abstract
Previous attempts to calculate hydrogen self- absorption in the solar flash-spectrum have used the earlier members of the Balmer series and essentially constructed emission curves-of- growth. Work on the Balmer decrement has been directed toward a solution for the b values, ignoring effects of self-absorption. It now seems that, for at least the higher series members, the Balmer decrement depends very little on the ba and essentially entirely upon the differential self- absorption. On this basis the self-absorption has been evaluated; and the number of hydrogen atoms, along a one square centimeter column in the line of sight, in the second level obtained. The value is 1.2 1016 atoms/cm1 at the eclipse height 670 km. The change of Balmer decrement with height gives the gradient of the population in this level. Combined with the equation of hydrostatic equilibrium, this gradient permits a rough estimate of the electron temperature gradient. The temperature gradient seems to be between I and 5 X I0-~ degrees/cm at the height 1000 km. Institute for Advanced Study, Princeton, N. J.
- Publication:
-
The Astronomical Journal
- Pub Date:
- September 1949
- DOI:
- 10.1086/106263
- Bibcode:
- 1949AJ.....54..196T