Carbon stars with silicate dust shells - I. Carbon stars with enhanced 13C (J stars).
Abstract
New optical observations show that three southern carbon stars with silicate dust shells are J stars, in addition to two already known from the Northern Hemisphere. Four more J stars have similar red IRAS colors although infrared spectra are lacking. A review of published data suggests that all the carbon stars with silicate shells may be J stars. These dust shells are all very red and must be optically thick, yet the carbon stars are not conspicuously reddened at optical wavelengths. The infrared sources are not very variable, although the probability is high that a companion of such red color would be a variable of large amplitude. It is suggested that material expelled from the carbon star, starting while it still had an oxygen-rich envelope, has accumulated in a disk around a hypothetical companion. The properties of J stars with silicate dust shells are consistent with this suggestion, while the unusual feature of the infrared sources are accounted for.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1990
- Bibcode:
- 1990MNRAS.243..336L
- Keywords:
-
- Carbon Stars;
- Carbon 13;
- Cosmic Dust;
- Silicates;
- Stellar Envelopes;
- Emission Spectra;
- Infrared Astronomy Satellite;
- Infrared Photometry;
- Light Curve;
- Optical Thickness;
- Stellar Spectrophotometry;
- Astrophysics