On the near-infrared excesses of very cool supergiants.
Abstract
Spectroscopic and narrowband photometry of a number of G, K and M supergiants with large IR excesses have been used to search for line weakening and chromospheric near-IR emission present in the peculiar M stars S Per, VY CMa, and VX Sgr. It is found that the line weakening of S Per and VX Sgr is probably photospheric in origin and temporally variable, while that of VY CMa may be constant. None of the other supergiants show significant line weakening. Veiling of the 4.8 micron absorption feature in late-type supergiants with extremely large IR excesses implies that the 3.5-8 micron excesses are formed above the molecular photospheres and are probably thermal reradiation from the circumstellar shells rather than free-free emission.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1977
- DOI:
- 10.1086/155669
- Bibcode:
- 1977ApJ...218..181F
- Keywords:
-
- Infrared Astronomy;
- Near Infrared Radiation;
- Stellar Spectrophotometry;
- Supergiant Stars;
- Absorption Spectra;
- Chromosphere;
- Emission Spectra;
- Interstellar Extinction;
- K Stars;
- Late Stars;
- Stellar Envelopes;
- Astrophysics