Teresa Gomez

A PHOTOMETRIC STUDY OF EARLY-TYPE STARS.

Observation data in the alpha16, Lambda9 photometric system are presented for 228 early-type O4-B8 stars of all luminosity classes. Also included are data for Be stars, B-type stars with a shell, and Beta Canis Majoris stars. The comparison with R-alpha and beta indices suggests that the alpha16 photometry is of good quality. The photometry can be used in separating different kinds of stars; when combined with the 13-color photometry, it makes possible a finer classification. The alpha16 index also provides an indication of stellar mass-loss rates, especially for supergiant stars. Preliminary He I (5876 A) measurements suggest that this line is well correlated with MK types. Be stars observed over several years also exhibit H-alpha line-strength variability. It is found that the Lambda9 index separates supergiant stars later than B2.