The Bright Part of the Luminosity Function for Halo Stars

Details The Bright Part of the Luminosity Function for Halo Stars The Bright Part of the Luminosity Function for Halo Stars

Oct 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995jkas...28..139l&link_type=abstract

Journal of the Korean Astronomical Society, vol. 28, no. 2, p. 139-146

Astronomy and Astrophysics

Astronomy

1

Halo Stars, Halo Luminosity Function, Subdwarfs, Mass Density

Scientific paper

The bright part of the halo luminosity function is derived from a sample of the 233 NLTT proper motion stars, which are selected by the 220km/sec of cutoff velocity in transverse to rid the contamination by the disk stars and corrected for the stars omitted in the sample by the selection criterion. It is limited to the absolute magnitude range of Mv = 4 - 8, but is based on the largest sample of halo stars up to now. This luminosity function provides a number density of 2.3e-5/pc3 and a mass density of 2.1e-5Mo/pc3 for 4 < Mv < 8 in the solar neighborhood. These are not sufficient for disk stability. The kinematics of the sample stars are = -7km/sec, = -228km/sec, and = -8km/sec with (sigma_u, sigma_v, simga_w) = (192,84,94)km/sec. The average metallicity of them is [Fe/H] = -1.7+-0.8. These are typical values for halo stars which are selected by the high cutoff velocity. We reanalyze the luminosity function for a sample of 57 LHS proper-motion stars. The newly derived luminosity function is consistent with the one derived from the NLTT halo stars, but gives a somewhat smaller number density for the absolute magnitude range covered by the LF from NLTT stars. The luminosity function based on the LHS stars seems to have a dip in the magnitude range corresponding to the Wielen Dip, but it also seems to have some fluctuations due to a small number of sample stars.