NOAO >   Observing Info >   Approved Programs >   2013A-0100

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Proposal Information for 2013A-0100


PI: Judith L. Provencal, University of Delaware, jlp@udel.edu
Address: Department of Physics and Astronomy, 104 The Green, Newark, DE 19716, USA

CoI: J. J. Hermes, University of Texas
CoI: M. Montgomery, University of Texas
CoI: Mike Reed, Missouri State University
CoI: Harry Shipman, University of Delaware
CoI: Luciano Fraga, SOAR (Southern Astrophysical Research Telescope)

Title: Empirical Determination of Convection in Pulsating White Dwarfs

Abstract: We propose high speed photometric observations of WD J1518+0658 with SOAR and the KPNO 2m as important components of a coordinated international campaign designed to survey the properties of convection in white dwarf atmospheres. Convection remains the largest source of theoretical uncertainty in our understanding of stellar physics. Asteroseismology has proven a powerful tool to attack this problem. White dwarf pulsations appear as local surface temperature variations. The extreme temperature sensitivity of convection leads to local variations in the convection zone's depth. This in turn modulates the local energy flux, producing nonsinusoidal light curves. The observed nonlinearities provide a self-consistent observational test of convection in white dwarf atmospheres. WD J1518+0658 is a member of the newly discovered class of extremely low mass white dwarf pulsators (ELMVs). ELMVs offer the opportunity to extend our investigation to unexplored regions of lower effective temperatures and surface gravities, where conditions are closer to those found in main sequence stars. High precision light curves from SOAR, combined with frequency, amplitude, and phase information provided by the KPNO 2m and the entire WET run, will allow us to recover WD J1518+0658's convective thermal response timescale.


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NOAO >   Observing Info >   Approved Programs >   2013A-0100

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