Measurements in the Combination Spectra of RW Hydrae, BF Cygni, and CI Cygni.
Abstract
This article describes a preliminary study of combination spectra with a dispersion of 10 A/mm. Two hundred and sizty measured emission lines are listed with their estimated intensities in four combination spectra. RW Hydrae.-Displacements of bright lines indicate a probable cycle of about 376 days. the observed interval the velocity-curve for the dark lines had a slope opposite to that of the bright lines, tending to support the binary-star hypothesis. The triplets of He I yielded velocities diffeting from those of the singlets. BF Cygni.-The rich bright-line spectrum presents many points of interest. Several lines of Fe U exhibited changing relative intensities that are difficult to ascribe to differences in population of the atomic levels concerned. Lines at X 4177.7 and X 6318.1 remain unidentified. CI Cygni.-Forbidden lines of the following ions were measured: 0 m, Ne ii', Ne v, Fe U, Fe v, Fe vi'. The permitted 0 m line X 3444 is sharp, while the [Ne v] line X 3425 is broad. This behavior differs from that regularly observed in planetary nebulae. Conctusions.-Systematic observations with fairly high dispersion will be required to reveal the true nature of "symbiotic" stars. Suggestions for future programs are included.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1950
- DOI:
- Bibcode:
- 1950ApJ...111..484M