ON THE EXISTENCE OF DA,F WHITE-DWARFS

The ideas and work presented in this paper date almost entirely from 1 977 when the original paper was submitted. The referee suggested that we check out several other strong northern candidates before publicati on, but upon resubmission several years later the editor noted that as it was now accepted that DA,F white dwarfs did not exist there was li ttle point in publishing the paper. In view of the fact that our prepr int was the main stimulus for this status change and reference to this work remains '1977 unpublished', we would like the paper to be publis hed and thus complete the historical record. Observations of some of t he stars considered by Weidemann as the most likely DA,F candidates ar e discussed together with theoretical computations of white dwarfs and subdwarfs. The reddest stars BPM 23251 and G 82-23 are shown to be K subdwarfs and L 532-81 (EG62) is a DA white dwarf. It is suggested tha t the DA,F stars, if they exist at all, are extremely rare and that th e metal abundance of the DA sequence may be less than 10-4 of the sola r abundance.