NOAO >   Observing Info >   Approved Programs >   2014A-0006

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Proposal Information for 2014A-0006


PI: Mukremin Kilic, University of Oklahoma, kilic@ou.edu
Address: Physics Department, 440 W Brooks Street, Norman, OK 73019, USA

CoI: J. J. Hermes, University of Warwick
CoI: Alexandros Gianninas, University of Oklahoma
CoI: Warren Brown, SAO

Title: A Search for Pulsating White Dwarf Companions to Millisecond Pulsars

Abstract: Our recent discovery of the first pulsating, extremely low mass white dwarfs (WDs) opens up a new discovery space for milli-second pulsar + WD systems. These are by far the coolest and the lowest-mass pulsating WDs, with temperatures of 7800-10,000 K and \logg=6-7. These stars greatly extend the DAV (or ZZ Ceti) instability strip, effectively bridging the gap in \log g between WDs and main-sequence stars. Curiously, there are two spectroscopically confirmed WD companions to millisecond pulsars (MSPs) that have similar temperature and surface gravity measurements as this newly discovered class of pulsators. To search for pulsations in one of these systems, we were awarded 4 h of Gemini South time in 2013B. Here we request 4 h of Gemini North time to obtain time-series photometry of the remaining target, which was in the restricted RA range in 2013B. If these WDs pulsate, they will be the first known examples of pulsating WD + pulsar binary systems. With two clocks in the system, we will be able to understand the interior structure of these helium-core WDs and accurately constrain the masses of both stars in the system, including the neutron star companions. Performing asteroseismology of a WD with an MSP companion affords an unprecedented constraint on the WD hydrogen layer mass, and thus its derived cooling age (and the pulsar's spin-down age).


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NOAO >   Observing Info >   Approved Programs >   2014A-0006

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