Spectral types of stars with unusual photometric indices.
Abstract
The Kitt Peak 2.1-m Cassegrain spectrograph was used to obtain spectra of 92 A5-G0 stars measured by Olsen in the Stromgren four-color system and predicted to be abnormal in the sense of excessive reddening, high luminosity, or abnormal composition. Of the five stars predicted to be reddened B or A stars, four were indeed such while for the fifth Olsen observed the blended components. Of twelve stars predicted to be supergiants, one is a supergiant, four are giants, two are subgiants, three are Ap stars, and two are Am stars. Thus photometrically predicted supergiants are actually stars above main sequence in two out of three cases but mostly much less luminous than expected. Of ten predicted weak-lined stars, only two were found to be really so. Am stars were well predicted, though detection is contaminated with Ap and luminous stars. It is concluded that four-color photometry is useful in selecting interesting stars, but is often unable to tell the specific type of abnormality present.
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- April 1979
- DOI:
- 10.1086/130467
- Bibcode:
- 1979PASP...91..176A
- Keywords:
-
- Giant Stars;
- Stellar Spectra;
- Stellar Spectrophotometry;
- Supergiant Stars;
- A Stars;
- Interstellar Extinction;
- Stellar Luminosity;
- Astronomy;
- Peculiar Stars:Spectral Classification;
- Peculiar Stars:Stroemgren Photometry