We present updated observations of a pilot survey of 14 pulsating DA white dwarfs, monitored for evidence of center-of-mass motion caused by a planetary companion. We have nearly doubled the number of periodicites for which we can produce O-C diagrams that document pulse arrival times from
our stars, and have implemented a method to minimize the apertures we use in our reductions in order to reduce sky noise. In addition to a previously published candidate, GD66, we have identi fed at least four more systems worthy
of rigorous observational follow-up. We have also implemented a method,
a generalized Lomb-Scargle periodogram, that takes into account weighted points in order to characterize any periodic behavior present in our O-C
diagrams.
For at least one DAV within this same sample, we have found strong
observational evidence for an evolutionary time scale (via the rate of period change) that is inconsistent with cooling alone. In that star, WD0111+0018, we report for the first time measurement of the rate of period change of nonlinear combination frequencies in a pulsating white dwarf. We speculate that this may be caused by a changing rotation rate that aff ects only modes with
m not equal to 0. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/ETD-UT-2010-08-1998 |
| Date | 17 December 2010 |
| Creators | Hermes, James Joseph, Jr. |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Type | thesis |
| Format | application/pdf |
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