Whole Earth Telescope observations of the subdwarf B star KPD 1930+2752: a rich, short-period pulsator in a close binary
| Autor: | Chris Cameron, Ömür Çakırlı, R. Avila, G. Stachowski, C. Akan, Y. M. Lipkin, S. L. Harms, Z. Csubry, Jaymie M. Matthews, M. Vuckovic, D. W. Winget, S. McDaniel, D. Zsuffa, Róbert Szabó, J. Bodnarik, R. Janulis, J. L. Provencal, M. Paparó, X.-J. Jian, M. Chevreton, Roy Ostensen, R. Pretorius, Michael D. Reed, J.-P. Gou, Fergal Mullally, Hong Wu, Reed Riddle, W. Ogloza, B. Berkey, H.-C. Lin, Wen Ping Chen, Philippe M. Binder, Pawel Moskalik, A. F. M. Costa, J.-E. Solheim, G. Vauclair, Roberto Silvotti, Ivan Bruni, R. Crowe, Kazuhiro Sekiguchi, S. G. Stewart, D. Terry, E. M. Leibowitz, C.-W. Chen, A. C. Quint, Zong-Li Liu, M. A. Morris, S. L. Kim, D. J. Sullivan, J. R. Eggen, S. Marinoni, S. Poindexter, Andrzej S. Baran, H. Pablo, D. W. Kurtz, Stanisław Zoła, N. Dolez, Steven D. Kawaler, Souza Oliveira Kepler, A.-Y. Zhou, D. Bolton |
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| Rok vydání: | 2011 |
| Předmět: |
Physics
Subdwarf B star 010308 nuclear & particles physics Phase (waves) White dwarf Binary number Astronomy and Astrophysics Astrophysics 01 natural sciences Subdwarf law.invention Telescope Amplitude 13. Climate action Space and Planetary Science law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Multiplet |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 412:371-390 |
| ISSN: | 0035-8711 |
| DOI: | 10.1111/j.1365-2966.2010.17912.x |
| Popis: | KPD 1930+2752 is a short-period pulsating subdwarf B (sdB) star. It is also an ellipsoidal variable with a known binary period just over two hours. The companion is most likely a white dwarf and the total mass of the system is close to the Chandresakhar limit. In this paper we report the results of Whole Earth Telescope (WET) photometric observations during 2003 and a smaller multisite campaign from 2002. From 355 hours of WET data, we detect 68 pulsation frequencies and suggest an additional 13 frequencies within a crowded and complex temporal spectrum between 3065 and 6343 $\mu$Hz (periods between 326 and 157 s). We examine pulsation properties including phase and amplitude stability in an attempt to understand the nature of the pulsation mechanism. We examine a stochastic mechanism by comparing amplitude variations with simulated stochastic data. We also use the binary nature of KPD 1930+2752 for identifying pulsation modes via multiplet structure and a tidally-induced pulsation geometry. Our results indicate a complicated pulsation structure that includes short-period ($\approx 16$ h) amplitude variability, rotationally split modes, tidally-induced modes, and some pulsations which are geometrically limited on the sdB star. |
| Databáze: | OpenAIRE |
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