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Title: Comparison of atmospheric parameters determined from spectroscopy and photometry for DA white dwarfs in the Sloan Digital Sky Survey

Abstract

We present a comparative analysis of atmospheric parameters obtained with the so-called photometric and spectroscopic techniques. Photometric and spectroscopic data for 1360 DA white dwarfs from the Sloan Digital Sky Survey (SDSS) are used, as well as spectroscopic data from the Villanova White Dwarf Catalog. We first test the calibration of the ugriz photometric system by using model atmosphere fits to observed data. Our photometric analysis indicates that the ugriz photometry appears well calibrated when the SDSS to AB{sub 95} zeropoint corrections are applied. The spectroscopic analysis of the same data set reveals that the so-called high-log g problem can be solved by applying published correction functions that take into account three-dimensional hydrodynamical effects. However, a comparison between the SDSS and the White Dwarf Catalog spectra also suggests that the SDSS spectra still suffer from a small calibration problem. We then compare the atmospheric parameters obtained from both fitting techniques and show that the photometric temperatures are systematically lower than those obtained from spectroscopic data. This systematic offset may be linked to the hydrogen line profiles used in the model atmospheres. We finally present the results of an analysis aimed at measuring surface gravities using photometric data only.

Authors:
Publication Date:
OSTI Identifier:
22370120
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 796; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CALIBRATION; CATALOGS; COMPARATIVE EVALUATIONS; CORRECTIONS; GRAVITATION; HYDROGEN; PHOTOMETRY; SPECTRA; SPECTROSCOPY; STELLAR ATMOSPHERES; SURFACES; THREE-DIMENSIONAL CALCULATIONS; WHITE DWARF STARS

Citation Formats

Genest-Beaulieu, C., and Bergeron, P., E-mail: genest@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca. Comparison of atmospheric parameters determined from spectroscopy and photometry for DA white dwarfs in the Sloan Digital Sky Survey. United States: N. p., 2014. Web. doi:10.1088/0004-637X/796/2/128.
Genest-Beaulieu, C., & Bergeron, P., E-mail: genest@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca. Comparison of atmospheric parameters determined from spectroscopy and photometry for DA white dwarfs in the Sloan Digital Sky Survey. United States. https://doi.org/10.1088/0004-637X/796/2/128
Genest-Beaulieu, C., and Bergeron, P., E-mail: genest@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca. 2014. "Comparison of atmospheric parameters determined from spectroscopy and photometry for DA white dwarfs in the Sloan Digital Sky Survey". United States. https://doi.org/10.1088/0004-637X/796/2/128.
@article{osti_22370120,
title = {Comparison of atmospheric parameters determined from spectroscopy and photometry for DA white dwarfs in the Sloan Digital Sky Survey},
author = {Genest-Beaulieu, C. and Bergeron, P., E-mail: genest@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca},
abstractNote = {We present a comparative analysis of atmospheric parameters obtained with the so-called photometric and spectroscopic techniques. Photometric and spectroscopic data for 1360 DA white dwarfs from the Sloan Digital Sky Survey (SDSS) are used, as well as spectroscopic data from the Villanova White Dwarf Catalog. We first test the calibration of the ugriz photometric system by using model atmosphere fits to observed data. Our photometric analysis indicates that the ugriz photometry appears well calibrated when the SDSS to AB{sub 95} zeropoint corrections are applied. The spectroscopic analysis of the same data set reveals that the so-called high-log g problem can be solved by applying published correction functions that take into account three-dimensional hydrodynamical effects. However, a comparison between the SDSS and the White Dwarf Catalog spectra also suggests that the SDSS spectra still suffer from a small calibration problem. We then compare the atmospheric parameters obtained from both fitting techniques and show that the photometric temperatures are systematically lower than those obtained from spectroscopic data. This systematic offset may be linked to the hydrogen line profiles used in the model atmospheres. We finally present the results of an analysis aimed at measuring surface gravities using photometric data only.},
doi = {10.1088/0004-637X/796/2/128},
url = {https://www.osti.gov/biblio/22370120}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 796,
place = {United States},
year = {Mon Dec 01 00:00:00 EST 2014},
month = {Mon Dec 01 00:00:00 EST 2014}
}