The Late A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation (original) (raw)
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Abstract
The MK spectral classification for late A-type stars is refined and the effects of rotation of spectral classification and uvby(beta) photometry for these stars are examined. It is found that, for A3 stars, the 4417/4481 A wavelength ratio produces results that are inconsistent with the Stark broadening of the H lines. It is suggested that this ratio is not useful as a luminosity criterion at any spectral type. Self-consistent sequences of narrow- and broadline standards are established. The results of the refined classification system are compared with Stromgren photometry, showing a set of low-v sin i A-type stars with anomalously large delta(c1) indices for their luminosity types. It is proposed that these stars are rapid rotators seen at fairly low inclination angles.
Publication:
The Astrophysical Journal Supplement Series
Pub Date:
July 1989
DOI:
Bibcode:
Keywords:
- A Stars;
- Astronomical Catalogs;
- Early Stars;
- Stellar Rotation;
- Stellar Spectrophotometry;
- Stellar Luminosity;
- Stellar Temperature;
- Ubv Spectra;
- Astrophysics;
- PHOTOMETRY;
- STARS: EARLY-TYPE;
- STARS: ROTATION;
- STARS: SPECTRAL CLASSIFICATION