Collapsed or Neutron Star Companions of Bright Stars

Abstract

Cameron¹ and Stothers² have suggested that the companion to ε Aurigae is a collapsed star. Epsilon Aurigae is one of several binary stars with large mass functions and invisible secondaries and so far the primaries of two of the brightest of these, ν Sgr (ref. 3) and β Lyrae, have been found to have helium-rich atmospheres. This shows that mass exchange has occurred, and that the visible star has been stripped down to its hydrogen deficient core by transferring matter into the vicinity of the former secondary. This explanation for ε Aur is the third of four possibilities discussed by Stothers. The proof of it would be the discovery of anomalously strong He I lines, such as λ5876, which appear in cool helium rich stars like R Cr B (ref. 4). This spectrpscopic check should be made.