Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs

Autor(en): Antonio Kanaan, Atsuko Nitta, Beverley J. Winget, S O Kepler, Michael H. Montgomery, Travis S. Metcalfe, H Oliveira, L Fraga, A. F M da Costa, J E S Costa, B G Castanheira, O Giovannini, R. Edward Nather, Anjum S. Mukadam, Steven D. Kawaler, M. Sean O'Brien, Mike D. Reed, Scot J. Kleinman, Judi L. Provencal, D Kilkenny, Denis J. Sullivan, Tiri Sullivan, B Shobbrook, Xianjun J. Jiang, B N Ashoka, S Seetha, Elia M. Leibowitz, P. A. Ibbetson, H Mendelson, Romualdas Kalytis, D Alisauskas, Darragh O'Donoghue, David A H Buckley, Peter Martinez, F van Wyk, R Stobie, F Marang, L van Zyl, W Ogloza, J Krzesinski, S Zola, Pawel A. Moskalik, Michel Breger, Anamarija Stankov, R Silvotti, A Piccioni, G Vauclair, Noel Dolez, M Chevreton, Jochen Lennart Deetjen, Stefan Dreizler, S L Schuh, J M Gonzalez Perez, Roy H. Ostensen, Ana Ulla, M Manteiga, O Suarez, Matthew R. Burleigh, Martin A. Barstow
Abstrakt: BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (?1.1 M?) to theoretically crystallize while still inside the ZZ Ceti instability strip (Teff ? 12000 K). As a consequence, this star represents our first opportunity to test crystallization theory directly. If the core is substantially crystallized, then the inner boundary for each pulsation mode will be located at the top of the solid core rather than at the center of the star, affecting mainly the average period spacing. This is distinct from the "mode trapping" caused by the stratified surface layers, which modifies the pulsation periods more selectively. In this paper we report on Whole Earth Telescope observations of BPM 37093 obtained in 1998 and 1999. Based on a simple analysis of the average period spacing we conclude that a large fraction of the total stellar mass is likely to be crystallized. Œ ESO 2005.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): University of Texas, Austin, Apache Point Observatory, Universidade Federal do Rio Grande do Sul, Universidade Federal de Santa Catarina, University of Washington, Iowa State University, Yale University, Case Western Reserve University, University of Delaware, South African Astronomical Observatory (SAAO), Victoria University of Wellington, The University of Sydney, Chinese Academy of Sciences (CAS), Indian Space Research Organization, Tel Aviv University, Vilnius University (VU), University of Cape Town, Pedagogical University of Cracow, Polish Academy of Sciences (PAS), COROT Additional Program Working Group, Università di Bologna, Observatoire Midi-Pyrénées, Université Toulouse III Paul Sabatier, Université de recherche Paris Sciences et Lettres, Eberhard Karls Universität Tübingen, Georg-August-Universität Göttingen, Universidad de Vigo, University of Leicester, Universität Wien
Journal: Astronomy & Astrophysics
Band: 432
Seiten: 219-224
Anzahl der Seiten: 6
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361:20041125
Publikationsdatum: 2005
Peer-reviewed: Ja
ÖFOS 2012: 1030 Physik, Astronomie
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/5c7a8f62-7130-4071-8a7c-fe6629136cfa

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