FM17p.07 — Time Series Photometric & Spectroscopic Observations of a Massive Crystallized White Dwarf Pulsator BPM37093

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Aug 10th at 6:00 PM until 6:00 PM

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Author(s): Atsuko Nitta1, S.O. Kepler5, Andre-Nicolas Chene1, D. Koester6, J.L. Provencal7, S.J. Kleinman1, D.J. Sullivan11, Paul Chote10, Ramotholo Sefako3, Antonio Kanaan4, Alejandra Romero5, Mariela Corti2, Mukremin Kilic8, M.H. Montgomery9, D.E. Winget9

Institution(s): 1. Gemini Observatory, 2. Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET),, 3. South African Astronomical Observatory, 4. Universidade Federal de Santa Catarina, 5. Universidade Federal do Rio Grande do Sul, 6. Universitat Kiel, 7. University of Delaware, 8. University of Oklahoma, 9. University of Texas at Austin, 10. University of Warwick, 11. Victoria University of Wellington

BPM37093 was the first of only a handful of massive (1.05+/-0.05 Msun; Bergeron 2004; Koester & Allard 2000) white dwarf pulsators discovered (Kanaan et al. 1992). These stars are particularly interesting because the crystallized mass-fraction as a function of mass and temperature is poorly constrained by observation, yet this process adds 1-2Gyr uncertainty in ages of the oldest white dwarf stars observed and hence, in the ages of associations that contain them (Althaus et al. 2012). We discovered that ESO uses BPM37093 as a standard star and extracted corresponding spectra from the public archive. The data suggested a large variation in the observed hydrogen line profiles that could potentially be due to pulsations, but the measurement did not reach a detection-quality threshold. To further explore this possibility, though, we obtained 4hrs of continuous time series spectroscopy of BPM37093 with Gemini in the Northern Spring of 2014. We present our results from these data along with those from the accompanying time series photometric observations we gathered from Mt.John (New Zealand), South African Astronomical Observatory (SAAO), Panchromatic Robotic optical Monitoring and Polarimetry Telescopes (PROMPT) in Chile, and Complejo Astronomico El Leoncito (Argentina) to support the Gemini observations.