8-12 juin, 2014


Testing the photometric calibration of SDSS using white dwarf stars

Cynthia Genest-Beaulieu (Département de physique, Université de Montréal)

Pierre Bergeron (Département de physique, Université de Montréal)

We present a method for testing the calibration of the ugriz photometric system of the Sloan Digital Sky survey (SDSS) using white dwarf stars. Our approach is based on a detailed comparison of the predicted synthetic photometry of hydrogen-line (DA) white dwarfs with the observed ugriz photometry drawn from the Data Release 7 of the SDSS. We also compare the resulting photometric temperature scale with effective temperatures obtained from fitting the observed hydrogen line profiles (the so-called spectroscopic technique) with our latest grid of model atmospheres and synthetic spectra. We also exploit the sensitivity of the Balmer jump to surface gravity, using the (u-g) color index, to study the log g distribution of DA white dwarfs, and in particular the well documented high-log g problem observed at low effective temperatures.

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