A survey of early-type stars based on the Two Micron All Sky Survey database

Abstract

We report the results of a spectroscopic survey of blue stars near the south Galactic pole, selected according to their color indices in the 2MASS database. The main scope of this work is to determine the nature of the objects that comprise the sample. Some characteristics of the Hβ, Hγ, and Hδ lines which are sensitive to temperature and gravity were measured and eventually compared with a grid of model atmospheres to obtain Teff and log g. In some cases the data allowed a unique, reliable classification of the star. Among the 44 stars studied, 5 objects are reliably classified as subdwarfs, 12 as A-type stars, and 3 as field horizontal-branch (FHB) stars. The remaining objects are either A or FHB stars, but additional observations are necessary to distinguish between these two types. Neither degenerate nor lowgravity stars (post-AGB) have been identified in the sample.