Commentary and Casual Observations on the SDSS DR7 Spectroscopic Sample

摘要

The SDSS DR7 sample of white dwarfs provides a very large and homogeneous spectroscopic population of relatively distant hot white dwarfs where the number of stars per unit distance peaks near 120 pc. This is in contrast to the local sample (< 20pc) of white dwarfs where the space density and the relative population of WD spectral types are well established. Although there is almost no spatial overlap between the SDSS sample and the local sample it is possible to draw some useful conclusions regarding the DR7 sample.