Red variable stars I. UBVRI photometry and photometric properties.
Abstract
In all phases of the light cycle of red variables stars, their near-infrared colors define a narrow sequence in the two color (V - R, R - I) diagram. This does not occur with other cool variable stars of types Ce, Se, and Ne. The position of a red variable on this sequence is very sensitive to the Me spectral type. The colors are molecular absorption indices, fundamentally of TiO, rather than indices of the color temperature. In general, the photometric magnitudes for a given Me star result from surfaces of different stellar radius and depend on the presence or absence of absorbing bands in the observed spectral continuum. This result is discussed in terms of amplitudes, radius, visual absolute magnitudes, and effective temperature, all of them free of or affected by TiO. Finally, these results give more information on which to build a model whose radial structure would have a relatively high stellar effective temperature and several cool covers of TiO molecules.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 1982
- DOI:
- 10.1086/113268
- Bibcode:
- 1982AJ.....87.1791C
- Keywords:
-
- Light Curve;
- M Stars;
- Stellar Spectrophotometry;
- Ubv Spectra;
- Variable Stars;
- Infrared Astronomy;
- Stellar Atmospheres;
- Stellar Temperature;
- Titanium Oxides;
- Astrophysics