Limitations on Physical Theories of H and K Emission Lines.
Abstract
A satisfactory physical theory of the H and K emission lines in the sun and stars has not yet been developed. By consideration of existing observations, certain requirements of and limitations upon such theories are established. If rO is the optical thickness in the line center, N the number of Ca ii ions per square centimeter vertical column, L the luminosity (visual), and AXD the Doppler width, the following items must be accounted for: A. Emission produced in optically thin layers (ro 1). (1) AXD L1/6. (2) N unrestricted except for upper limit on ro. (3) Mechanism for adequate emission from thin layers. B. Emission produced in optically thick layers (10 < ro <- l0 ). (1) Both AXD and N must vary appropriately with L. (2) The rate of variation of AXD with L must lie within the maximum and minimum rates, which, together with the corresponding variations of N, are, respectively, AXD L1/5, N L-1/4, and AXD L1/9, N L1/2.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1957
- DOI:
- 10.1086/146426
- Bibcode:
- 1957ApJ...126..525W