EDP Sciences
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Volume 381, Number 1, January I 2002
Page(s) 122 - 150
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011483

A&A 381, 122-150 (2002)
DOI: 10.1051/0004-6361:20011483

Asteroseismology of RXJ 2117+3412, the hottest pulsating PG 1159 star

G. Vauclair1, P. Moskalik2, B. Pfeiffer1, M. Chevreton3, N. Dolez1, B. Serre1, S. J. Kleinman4, 5, M. Barstow6, A. E. Sansom6, J.-E. Solheim7, J. A. Belmonte8, S. D. Kawaler9, S. O. Kepler10, A. Kanaan10, 11, O. Giovannini10, D. E. Winget4, T. K. Watson4, R. E. Nather4, J. C. Clemens4, 12, J. Provencal4, 13, J. S. Dixson4, K. Yanagida4, A. Nitta Kleinman4, M. Montgomery4, E. W. Klumpe4, A. Bruvold7, M. S. O'Brien9, 14, C. J. Hansen15, A. D. Grauer16, P. A. Bradley4, 17, 18, M. A. Wood19, 18, N. Achilleos20, S. Y. Jiang21, J. N. Fu1, 21, T. M. K. Marar22, B. N. Ashoka22, E. G. Meistas23, A. V. Chernyshev24, T. Mazeh25, E. Leibowitz25, S. Hemar25, J. Krzesinski26, G. Pajdosz26 and S. Zola26, 27

1  Université Paul Sabatier, Observatoire Midi-Pyrénées, CNRS/UMR5572, 14 Av. É. Belin, 31400 Toulouse, France
2  Copernicus Astronomical Center, Ul. Bartycka 18, 00-716 Warsaw, Poland
3  Observatoire de Paris-Meudon, DAEC, 92195 Meudon, France
4  Department of Astronomy and McDonald Observatory, Texas University at Austin, Austin, TX 78712, USA
5  Sloan Digital Sky Survey, Apache Pt. Observatory, PO Box 59, Sunspot, NM 88349, USA
6  Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
7  Department of Physics, University of Tromso, 9037 Tromso, Norway
8  Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife, Spain
9  Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
10  Instituto de Física-UFRGS, Av. B. Goncalves 9500, 91501-900 Porto-Alegre, RS, Brazil
11  Departamento de Física, Universidade Federal de Santa Catarina, CP 476, CEP 88040-900, Florianópolis, Brazil
12  Department of Physics, University of North Carolina, Chapel Hill, NC 27599-3255, USA
13  Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
14  Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
15  Joint Institute for Laboratory Astrophysics, University of Colorado, Box 440, Boulder, CO 80309, USA
16  Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204, USA
17  Los Alamos National Laboratory, X-2, MS B-220, Los Alamos, NM 87545, USA
18  Guest Observer, Institute for Astronomy, Honolulu, HI, USA
19  Department of Physics and Space Sciences and SARA Observatory, Florida Institute of Technology, Melbourne, FL 32901, USA
20  Siding Spring Observatory, and Department of Mathematics, Australian National University, Canberra, Australia
21  Beijing Astronomical Observatory, Chinese Academy of Sciences, 20A, Datun Road, Beijing 100012, PR China
22  Indian Space Research Organization, Airport Road, Vimanapura PO, Bangalore 560017, India
23  Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius 2600, Lithuania
24  Astronomical Institute, Astronomicheskaya 33, Tashkent 700052, Uzbekistan
25  Wise Observatory, Tel Aviv University, Tel Aviv 69978, Israel
26  Mt. Suhora Observatory, Cracow Pedagogical University, Ul. Podchorazych 2, 30-084 Cracow, Poland
27  Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Cracow, Poland

(Received 17 July 2001 / Accepted 15 October 2001 )

The pulsating PG 1159 planetary nebula central star RXJ 2117+3412 has been observed over three successive seasons of a multisite photometric campaign. The asteroseismological analysis of the data, based on the 37 identified $\ell=1$ modes among the 48 independent pulsation frequencies detected in the power spectrum, leads to the derivation of the rotational splitting, the period spacing and the mode trapping cycle and amplitude, from which a number of fundamental parameters can be deduced. The average rotation period is $1.16\pm 0.05$ days. The trend for the rotational splitting to decrease with increasing periods is incompatible with a solid body rotation. The total mass is 0.56 +0.02-0.04  $M_{\odot}$ and the He-rich envelope mass fraction is in the range 0.013-0.078  M*. The luminosity derived from asteroseismology is log( $L/L_{\odot})= 4.05$  +0.23-0.32 and the distance 760  +230-235 pc. At such a distance, the linear size of the planetary nebulae is $2.9\pm 0.9$ pc. The role of mass loss on the excitation mechanism and its consequence on the amplitude variations is discussed.

Key words: stars: fundamental parameters -- stars: individual (RXJ 2117+3412) -- stars: oscillations

Offprint request: G. Vauclair, gerardv@obs-mip.fr

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© ESO 2002