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A second case of outbursts in a pulsating white dwarf observed by Kepler
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Hermes, J. J., Montgomery, M. H., Bell, Keaton J., Chote, Paul, Gänsicke, B. T. (Boris T.), Kawaler, Steven D., Clemens, J. Christopher, Dunlap, Bart H., Winget, D. E. and Armstrong, David J. (2015) A second case of outbursts in a pulsating white dwarf observed by Kepler. The Astrophysical Journal, 810 (1). pp. 1-6. L5. doi:10.1088/2041-8205/810/1/L5
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Official URL: http://dx.doi.org/10.1088/2041-8205/810/1/L5
Abstract
We present observations of a new phenomenon in pulsating white dwarf stars: large-amplitude outbursts at timescales much longer than the pulsation periods. The cool (${T}_{\mathrm{eff}}$ = 11,060 K), hydrogen-atmosphere pulsating white dwarf PG 1149+057 was observed nearly continuously for more than 78.8 day by the extended Kepler mission in K2 Campaign 1. The target showed 10 outburst events, recurring roughly every 8 day and lasting roughly 15 hr, with maximum flux excursions up to 45% in the Kepler bandpass. We demonstrate that the outbursts affect the pulsations and therefore must come from the white dwarf. Additionally, we argue that these events are not magnetic reconnection flares, and are most likely connected to the stellar pulsations and the relatively deep surface convection zone. PG 1149+057 is now the second cool pulsating white dwarf to show this outburst phenomenon, after the first variable white dwarf observed in the Kepler mission, KIC 4552982. Both stars have the same effective temperature, within the uncertainties, and are among the coolest known pulsating white dwarfs of typical mass. These outbursts provide fresh observational insight into the red edge of the DAV instability strip and the eventual cessation of pulsations in cool white dwarfs.
| Item Type: | Journal Article | ||||||||
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| Subjects: | Q Science > QB Astronomy | ||||||||
| Divisions: | Faculty of Science > Physics | ||||||||
| Library of Congress Subject Headings (LCSH): | Stars -- Evolution, Stellar oscillations, White dwarf stars | ||||||||
| Journal or Publication Title: | The Astrophysical Journal | ||||||||
| Publisher: | Institute of Physics Publishing, Inc. | ||||||||
| ISSN: | 0004-637X | ||||||||
| Official Date: | 24 August 2015 | ||||||||
| Dates: |
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| Volume: | 810 | ||||||||
| Number: | 1 | ||||||||
| Number of Pages: | 6 | ||||||||
| Page Range: | pp. 1-6 | ||||||||
| Article Number: | L5 | ||||||||
| DOI: | 10.1088/2041-8205/810/1/L5 | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||
| Funder: | European Research Council (ERC), Seventh Framework Programme (European Commission) (FP7), National Science Foundation (U.S.) (NSF), United States. National Aeronautics and Space Administration (NASA) | ||||||||
| Grant number: | 320964 (FP7), AST-1312983 (NSF), NNX12AC96G (NASA) | ||||||||
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