Extreme ultraviolet explorer optical identification campaign .3. A southern hemisphere sample of active late-types stars and white dwarfs

We present optical identifications of 30 previously unidentified extreme ultraviolet (EUV) and soft x-ray sources coinciding with the position of faint sources detected during the all-sky surveys of the Extreme Ultraviolet Explorer (EUVE) in the 58-174 Angstrom (0.071-0.214 keV) band and of the ROSAT Position Sensitive Proportional Counter (PSPC) in the 5-120 Angstrom (0.1-2.4 keV x-ray) band. We present low-resolution spectra of the possible optical counterparts of the x-ray and EUVE sources obtained with 1.5 m telescope at CTIO in 1995 May and December and 1996 February. The optical counterparts for 23 sources are identified as late-type (dKe and dMe) stars, and 4 are identified as new DA white dwarfs. All spectra of sources identified as late-type stars show the Balmer series and Ca H and K lines in emission, indicating the signature of chromospheric activity. For the white dwarfs, the joint detection by the ROSAT PSPC and the EUVE Lexan band indicates that they have a low-abundance of metals and that their EUV emission is mostly attenuated by the local interstellar medium (ISM). (C) 1997 American Astronomical Society.