The Shell Spectrum of HR 8731 IN 1940, with an Intercomparison of the Spectra of Several Shells.
Abstract
The 1940 shell spectrum of HR 8731 was very similar to that of ~ Tauri in 1914. This paper presents an analysis of the spectrum in which lines of H, 0 i, Mg i, Mg II, Si ii, Ca i, Ca ii, Ti ii, Cr ii, Fe i, Fe ii, Sr ii, Sc ii, and Ni ii were identified. It is suggested that HR 8731 may be the brighter component of a long-period binary. When the shell spectra of y Cassiopeiae, ~ Tauri, Capricorni, ~ Monocerotis, Pleione, HR 8731, and ~& Persei are compared it is found that they can be arranged, as above, in order of decreasing excitation conditions in the shell. The primary difference between various shells is one of ionization rather than composition. Usually the cooler shells contain less material, i.e., the shell absorption lines are weak
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1943
- DOI:
- 10.1086/144528
- Bibcode:
- 1943ApJ....97..388B