Kinematics and luminosity function of dwarf populations in three areas of the Calan-ESO proper-motion catalog.
ROJO P. and RUIZ M.T.
Abstract (from CDS):
We have completed the analysis of a sample of 112 stars in the solar neighborhood taken from the statistically complete Calán-ESO catalog. From medium-resolution spectroscopy we classified every star, both by direct comparison with spectroscopic standards and by using spectral indices. The latter also allowed discrimination between main-sequence (MS) dwarfs and subdwarfs. Several useful spectral type versus color relations were obtained from CCD photometry of the sample (observed magnitudes were dereddened). Distances and absolute magnitudes were determined. From measured radial velocities and proper motions, we determined the kinematics [Galactocentric velocity components (U,V,W)], which allowed the classification of each star as belonging to the disk or halo population. Luminosity functions (LFs) were then obtained using the 1/Vmaxmethod for the different populations. The maximum in the LF for MS dwarfs was found to be near MV=12.5±0.5, in accord with previous determinations. On the other hand, we found an increase in the LF of the subdwarf at its faint end, which is in strong disagreement with determinations by other authors. A mass density of MS dwarfs of ∼0.047±0.021 M☉pc–3 was derived, while the contribution of subdwarfs was found to be negligible.