Time Series Photometric anda Spectroscopic Observations of the Massive Crystalized White Dwarf Pulsator BPM 37093

NITTA ATSUKO; KEPLER, S.O.; ANDRÉ-NICHOLAS CHENÉ; ET AL.; CORTI MARIELA; ET AL.

Congreso; XXIXh IAU General Assembly; 2015

We are trying to reduce the largest uncertainties in using white dwarf stars as Galac-tic chronometers by understanding the details of carbon crystalliazation that currently result ina 1{2 Gyr uncertainty in the ages of the oldest white dwarf stars. We expect the coolest whitedwarf stars to have crystallized interiors, but theory also predicts hotter white dwarf stars, if theyare massive enough, will also have some core crystallization. BPM 37093 is the rst discoveredof only a handful of known massive white dwarf stars that are also pulsating DAV, or ZZ Ceti,variables. Our approach is to use the pulsations to constrain the core composition and amountof crystallization. Here we report our analysis of 4hrs of continuous time series spectroscopy ofBPM 37093 with Gemini South combined with simultaneous time-series photometry from Mt.John (New Zealand), SAAO, PROMPT, and Complejo Astronomico El Leoncito (CASLEO,ARGENTINA)