.. _book_fig_chapter1_fig_SDSS_sspp:


SDSS Segue Stellar Parameter Pipeline Data
------------------------------------------
Figure 1.5.

The surface gravity vs. effective temperature plot for the first 10,000 entries
from the catalog of stars with SDSS spectra. The rich substructure reflects
both stellar physics and the SDSS selection criteria for spectroscopic
follow-up. The plume of points centered on Teff ~ 5300 K and log g ~ 3 is
dominated by red giant stars, and the locus of points with Teff < 6500 K and
log g > 4.5 is dominated by main sequence stars. Stars to the left from the
main sequence locus are dominated by the so-called blue horizontal branch
stars. The axes are plotted backward for ease of comparison with the classical
Hertzsprung-Russell diagram: the luminosity of a star approximately increases
upward in this diagram.



.. image:: ../images/chapter1/fig_SDSS_sspp_1.png
    :scale: 100
    :align: center


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