New high-proper motion survey in the Southern sky

We present the discovery of about 100 new high-proper motion stars in the r egion between 0(h) and 7(h) in right ascension and -63 degrees and -32 degr ees in declination, with proper motions between 0.3 and 1.0 arcsec/yr. In a ddition we have obtained improved coordinates and photographic photometry f or another about 100 already known high-proper motion stars in the same reg ion. In this study we have made use of APM measurements of UKST survey plat es in 40 survey fields. Using all available information (position, proper m otion, photographic R magnitude and B-J - R colour index), we draw some pre liminary conclusions on the nature of the new high-proper motion stars, par ticularly of extreme cases. In addition, for some of the new high-proper mo tion stars we carried out low resolution optical spectroscopy with the 1.9m Radcliffe telescope of the South Africa Astronomical Observatory (SAAO). T he faintest discovered proper motion stars are a common proper motion pair with mu = 0.5 arcsec/yr, R magnitudes of 19.7 and 20.9 and B-J magnitudes o f 20.6 and 22.9, respectively. A first estimate of the absolute magnitude o f this proper motion pair APMPM J0352-4127AB based on estimating the distan ce from the extant observational data, yields M-V - 15.8 +/- 2.3 and M-V = 18.1 +/- 2.3, respectively for the two components. We conclude that both co mponents are likely to be extremely cool degenerate white dwarfs. The SAAO spectrum of the brighter component is a first confirmation of the cool whit e dwarf nature, although the signal-to-noise was very low. There are other cool white dwarfs among the stars for which SAAO spectra were obtained. The star with the largest proper motion among the newly detected proper motion stars (mu = 0.95 arcsec/yr and R = 15.8; B-J - R = 2.2) had a spectrum cor responding to a mid-M dwarf. For the extremely red (B-J - R > 2.6) and blue (B-J - R < 0.7) stars in our sample, our prior assumptions based on photom etry and proper motion of late type M dwarf or normal white dwarf nature re spectively, were confirmed by follow-up spectroscopy obtained at the SAAO. We have also obtained relatively blight stars (11 < R < 14) with roper moti ons between 0.3 and 0.8 arcsec/yr, formerly not recognised as high-proper m otion stars. The star with the largest proper motion among these new bright high-proper motion stars (R = 13.4, mu = 0.77 arcsec/yr) was identified wi th the bright X-ray source 1RXS J023630.5-592827 and classified as a nearby (distance = 12 pc) active M5 dwarf (Scholz et al. 1999).