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TwitterA&A 477, 627-640 (2008)
DOI: 10.1051/0004-6361:20053470
The pulsation modes of the pre-white dwarf PG 1159-035
J. E. S. Costa1, S. O. Kepler1, D. E. Winget2, M. S. O'Brien3, S. D. Kawaler4, A. F. M. Costa1, O. Giovannini1, 5, A. Kanaan6, A. S. Mukadam7, F. Mullally2, A. Nitta8, J. L. Provençal9, H. Shipman9, M. A. Wood10, T. J. Ahrens10, A. Grauer11, M. Kilic12, P. A. Bradley13, K. Sekiguchi14, R. Crowe15, X. J. Jiang16, D. Sullivan17, T. Sullivan17, R. Rosen17, J. C. Clemens18, R. Janulis19, D. O'Donoghue20, W. Ogloza21, A. Baran21, R. Silvotti22, S. Marinoni23, G. Vauclair24, N. Dolez24, M. Chevreton25, S. Dreizler26, 27, S. Schuh26, 27, J. Deetjen26, T. Nagel26, J.-E. Solheim28, 29, J. M. Gonzalez Perez28, 30, A. Ulla31, M. Barstow32, M. Burleigh32, S. Good32, T. S. Metcalfe33, S.-L. Kim34, H. Lee34, A. Sergeev35, M. C. Akan36, Ö. Çakirli36, M. Paparo37, G. Viraghalmy37, B. N. Ashoka38, G. Handler39, Ö. Hürkal40, F. Johannessen28, S. J. Kleinman8, R. Kalytis19, J. Krzesinski21, E. Klumpe41, J. Larrison41, T. Lawrence4, E. Meistas19, P. Martinez20, R. E. Nather2, J.-N. Fu42, E. Pakstiene19, R. Rosen28, E. Romero-Colmenero20, R. Riddle43, S. Seetha39, N. M. Silvestri7, M. Vuckovic4, 44, B. Warner20, S. Zola45, L. G. Althaus46, 47, A. H. Córsico46, 47, and M. H. Montgomery21 Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil
e-mail: costajes@gmail.com
2 Department of Astronomy & McDonald Observatory, University of Texas, Austin, TX 78712, USA
3 Department of Astronomy, Yale University, New Haven, Connecticut, CT 06851, USA
e-mail: obrien@astro.yale.edu
4 Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
5 Universidade de Caxias, Caxias do Sul, RS, Brazil
6 Departamento de Fíica, Universidade Federal de Santa Catarina, CP 476, CEP 88040-900, Florianópolis, SC, Brazil
e-mail: kanaan@fsc.ufsc.br
7 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA
e-mail: nms@astro.washington.edu
8 Gemini Observatory, Hilo, Hawaii, 96720, USA
9 Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
10 Dept. of Physics and Space Sciences & The SARA Observatory, Florida Institute of Technology, Melbourne, FL 32901, USA
11 Department of Physics and Astronomy, University of Arkansas at Little Rock, USA
12 Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210, USA
e-mail: kilic@astronomy.ohio-state.edu
13 Los Alamos National Laboratory, X-2, MS T-085 Los Alamos, NM 87545, USA
14 Subaru National Astronomical Observatory of Japan, Mitaka, Tokyo 181, Japan
e-mail: kaz@saburu.naoj.org
15 University of Hawaii, Hilo, Hawaii, USA
16 Beijing Astronomical Observatory, Academy of Sciences, Beijing 100080, PR China
e-mail: jiang@astro.as.utexas.edu
17 University of Victoria, Wellington, New Zealand
18 University of North Carolina, Chapell Hill, NC 27599, USA
19 VU Institute of Theoretical Physics and Astronomy, Gostauto 12, 01108 Vilnius, Lithuania
20 South African Astronomical Observatory
21 Mt. Suhora Observatory, Cracow Pedagogical University, UI. Podchorazych 2, 30-084 Cracow, Poland
22 INAF - Osservatorio Astronomico di Capodimonte, Napoli, Italy
23 INAF - Osservatorio Astronomico di Bologna, Bologna, Italy
24 Université Paul Sabatier, Observatoire Midi-Pyrénées, CNRS/UMR5572, 14 Av. E. Belin, 31400 Toulouse, France
25 Observatoire de Paris-Meudon, DAEC, 92195 Meudon, France
e-mail: chevreton@obspm.fr
26 Institut für Astrophysik,Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
27 Institut für Astronomie und Astrophysik Tübingen, Universitat Tübingen, Sand 1, 72076 Tübingen, Germany
28 Institutt for Fysikk, Universitetet i Tromsø, 9037 Tromsø, Norway
e-mail: j.e.solheim@astro.uio.no
29 Institut for Teoretisk Astrofysikk, Universitetet i Oslo, pb 1029-Blindern, 0315 Oslo, Norway
30 Instituto de Astrofisica, C/ via Lactea s/n, 38200 La Laguna, Tenerife, Spain
31 Universidade de Vigo, Depto. de Física Aplicada, Facultade de Ciencias do Mar, Campus Lagoas-Marcosende s/n, 36200 Vigo, Spain
32 Department of Physics and Astronomy, University of Leicester, UK
33 High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green Dr (CG1/3164), USA
e-mail: travis@hao.ucar.edu
34 Korea Astronomy and Space Science Institute, Daejeon, 305-348, Korea
35 Terskol Observatory, Ukraine
36 Ege University Observatory, Bornova 35100, Izmir, Turkey
37 Konkoly Observatory, PO Box 67, 1525 Budapest, Hungary
38 Indian Space Research Organization, India
39 Institut für Astronomie, Universität Wien, Turkenschanzstrasse 17, 1180 Wien, Austria
40 Ege University Faculty of Science Astronomy and Space Sciences Department, Izmir, Turkey
41 Middle Tennessee State University, Department of Physics and Astronomy Murfreesboro, TN 37132, USA
42 Department of Astronomy, Beijing Normal University, Beijing, PR China
43 Thirty Meter Telescope Project, 2632 E. Washington Blvd, Pasadena, CA 91107, USA
e-mail: riddle@tmt.org
44 Instituut voor Sterrenkunde, Celestijnenlaan 200B, 3001 Leuven, Belgium
e-mail: Maja.Vuckovic@ster.kuleuven.be
45 Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Krakow, Poland
e-mail: szola@oa.uj.edu.pl
46 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, (1900) La Plata, Argentina
e-mail: [althaus;acorsico]@fcaglp.unlp.edu.ar
47 Instituto de Astrofísica La Plata, IALP, CONICET-UNLP, Argentina
(Received 18 May 2005 / Accepted 31 October 2007)
Abstract
Context.
PG 1159-035
, a pre-white dwarf with
140 000 K,
is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV
pulsating class.
Previous studies of
PG 1159-035
photometric data obtained
with the Whole Earth Telescope (WET) showed a rich frequency spectrum
allowing the identification of 122 pulsation modes.
Analyzing the periods of pulsation,
it is possible to measure the stellar mass, the rotational
period and the inclination of the rotation axis, to estimate an upper
limit for the magnetic field, and even to obtain information about
the inner stratification of the star.
Aims.We have three principal aims: to increase the number of detected and identified pulsation modes
in
PG 1159-035
, study trapping of the star's pulsation modes, and to improve or constrain
the determination of stellar parameters.
Methods.We used all available WET photometric data from 1983, 1985, 1989, 1993 and 2002
to identify the pulsation periods.
Results.We identified 76 additional pulsation modes, increasing to 198 the number of known pulsation modes
in
PG 1159-035
, the largest number of modes detected in any star besides the Sun.
From the period spacing we estimated a mass 
= 0.59 
0.02 for
PG 1159-035
, with the uncertainty dominated by the models, not the observation.
Deviations in the regular period spacing suggest that
some of the pulsation modes are trapped,
even though the star is a pre-white dwarf and the gravitational settling is ongoing.
The position of the transition zone that causes the mode trapping
was calculated at
= 0.83 0.05.
From the multiplet splitting, we calculated the rotational period
= 1.3920 0.0008 days and an upper limit for the magnetic field, B < 2000 G. The total power of the pulsation modes at the stellar surface changed less than 30%
for 
= 1 modes and less than 50% for = 2 modes.
We find no evidence of linear combinations between the 198 pulsation mode frequencies.
PG 1159-035
models have not significative convection zones,
supporting the hypothesis that nonlinearity arises in the
convection zones in cooler pulsating white dwarf stars.
Key words: stars: oscillations -- stars: individual: PG 1159-035 -- stars: interiors -- stars: white dwarfs
© ESO 2007