The Helium-Weak Stars

In an extensive investigation of spectral classification, the class of helium-weak stars is described. Their spectra are found to resemble the Bp-type stars with the distinction that the helium-weak group does not have the profuse and strongly enhanced metal lines characteristic of the Bp stars. In a quantitative analysis using model atmospheres, several helium-weak stars are found to have apparent helium deficiencies (NH /NH 0.02). On the other hand, RD 37129, RD 36629, and RD 37807, previously classified as "helium-weak,', appear to be normal early B-type stars-a conclusion which was also found by Norris.