Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

Autor(en): Gerald Handler, Darragh O'Donoghue, M Müller, Jan Erik Solheim, J M Gonzalez Perez, F Johannessen, Margit Paparó, B Szeidl, G Viraghalmy, R Silvotti, G Vauclair, Noel Dolez, E Pallier, M Chevreton, Donald W. Kurtz, Gordon E. Bromage, Margarida S. Cunha, Roy H. Ostensen, L Fraga, Antonio Kanaan, A Amorim, O Giovannini, S O Kepler, A. F M da Costa, R F Anderson, Matt A. Wood, Nicole M. Silvestri, Eric W. Klumpe, Robert F. Carlton, R H Miller, J P McFarland, Albert D. Grauer, Steven D. Kawaler, Reed L. Riddle, Mike D. Reed, R. Edward Nather, Beverley J. Winget, J A Hill, Travis S. Metcalfe, Anjum S. Mukadam, M Kilic, Todd K. Watson, Scot J. Kleinman, Atsuko Nitta, Joyce Ann Guzik, Paul A. Bradley, Kazuhiro Sekiguchi, Denis J. Sullivan, Tiri Sullivan, R R Shobbrook, Xianjun J. Jiang, Peter V. Birch, B N Ashoka, S Seetha, V Girish, Santosh Joshi, Tatyana N Dorokhova, N I Dorokhov, M. Can Akan, E G Meistas, R Janulis, Romualdas Kalytis, D Alisauskas, S K Anguma, P Kalebwe, Pawel A. Moskalik, W Ogloza, Greg Stachowski, G Pajdosz, S Zola
Abstrakt: We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these data plus all available archival measurements to study the temporal behaviour of the pulsational amplitudes and frequencies of these stars for the first time. We demonstrate that both KUV 05134+2605 and PG 1654+160 pulsate in many modes, the amplitudes of which are variable in time; some frequency variability of PG 1654+160 is also indicated. Beating of multiple pulsation modes cannot explain our observations; the amplitude variability must therefore be intrinsic. We cannot find stable modes to be used for determinations of the evolutionary period changes of the stars. Some of the modes of PG 1654+160 appear at the same periods whenever detected. The mean spacing of these periods (˜40 s) suggests that they are probably caused by non-radial gravity-mode pulsations of spherical degree 1 = 1. If so, PG 1654+160 has a mass around 0.6 M?. The time-scales of the amplitude variability of both stars (down to two weeks) are consistent with theoretical predictions of resonant mode coupling, a conclusion which might however be affected by the temporal distribution of our data.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): University of Cape Town, University of Oslo (UiO), University of Tromsø - The Arctic University of Norway, Hungarian Academy of Sciences, COROT Additional Program Working Group, Observatoire Midi-Pyrénées, Université Toulouse III Paul Sabatier, Laboratoire d’Astrophysique de Toulouse-Tarbes, Université de recherche Paris Sciences et Lettres, University of Central Lancashire, Universidade do Porto, Universidade Federal de Santa Catarina, University of Texas, Austin, Universidade Federal do Rio Grande do Sul, University of North Carolina at Chapel Hill, Florida Institute of Technology, University of Washington, Middle Tennessee State University (MTSU), Georgia State University, University of Arkansas at Little Rock, Iowa State University, Case Western Reserve University, Kitt Peak National Observatory, Southwestern University, Apache Point Observatory, Los Alamos National Laboratory, Subaru Telescope, Victoria University of Wellington, Australian National University, Chinese Academy of Sciences (CAS), Perth Observatory, Indian Space Research Organization, Uttar Pradesh State Observatory, Odessa Astronomical Observatory, EGE University, Vilnius University (VU), University of British Columbia (UBC), University of Zambia, Polish Academy of Sciences (PAS), Pedagogical University of Cracow
Journal: Monthly Notices of the Royal Astronomical Society
Band: 340
Seiten: 1031-1038
Anzahl der Seiten: 8
ISSN: 0035-8711
DOI: https://doi.org/10.1046/j.1365-8711.2003.06373.x
Publikationsdatum: 2003
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie
Link zum Portal: https://ucris.univie.ac.at/portal/de/publications/amplitude-and-frequency-variability-of-the-pulsating-db-white-dwarf-stars-kuv-051342605-and-pg-1654160-observed-with-the-whole-earth-telescope(c26437d4-e323-473a-94d9-2121034486bb).html

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