Costa, J. E. S. and Kepler, S. O. and Winget, D. E. and O'Brien, M. S. and Kawaler, S. D. and Costa, A. F. M. and Giovannini, O. and Kanaan, A. and Mukadam, A. S. and Mullally, F. and Nitta, A. and Provençal, J. L. and Shipman, H. and Wood, M. A. and Ahrens, T. J. and Grauer, A. and Kilic, M. and Bradley, P. A. and Sekiguchi, K. and Crowe, R. and Jiang, X. J. and Sullivan, D. and Sullivan, T. and Rosen, R. and Clemens, J. C. and Janulis, R. and O'Donoghue, D. and Ogloza, W. and Baran, A. and Silvotti, R. and Marinoni, S. and Vauclair, G. and Dolez, N. and Chevreton, M. and Dreizler, S. and Schuh, S. and Deetjen, J. and Nagel, T. and Solheim, J.-E. and Gonzalez Perez, J. M. and Ulla, A. and Barstow, M. and Burleigh, M. and Good, S. and Metcalfe, T. S. and Kim, S.-L. and Lee, H. and Sergeev, A. and Akan, M. C. and Çakirli, Ö. and Paparo, M. and Viraghalmy, G. and Ashoka, B. N. and Handler, G. and Hürkal, Ö. and Johannessen, F. and Kleinman, S. J. and Kalytis, R. and Krzesinski, J. and Klumpe, E. and Larrison, J. and Lawrence, T. and Meistas, E. and Martinez, P. and Nather, R. E. and Fu, J.-N. and Pakstiene, E. and Rosen, R. and Romero-Colmenero , E. and Riddle, R. and Seetha, S. and Silvestri, N. M. and Vuckovic, M. and Warner, B. and Zola, S. and Althaus, L. G. and Córsico , A. H. and Montgomery, M. H. (2008) The pulsation modes of the pre-white dwarf PG 1159-035. Astronomy and Astrophysics, 477 (2). pp. 627-640. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20090925-085032172
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Context. PG 1159-035, a pre-white dwarf with T_(eff) ≃ 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 M/M_⊙ = 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 r_c/R_* = 0.83 ± 0.05. From the multiplet splitting, we calculated the rotational period P_(rot) = 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 ℓ = 1 modes and less than 50% for ℓ = 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.
|Additional Information:||© ESO 2007. Received 18 May 2005. Accepted 31 October 2007. This work was partially supported by CNPq-Brazil, NSFUSA and MCyT-Spain. In particular, M. H. Montgomery was supported by NSF grant AST-0507639.|
|Subject Keywords:||stars : oscillations; stars : individual : PG 1159-035; stars : interiors; stars : white dwarfs|
|Official Citation:||The pulsation modes of the pre-white dwarf PG 1159-035 J. E. S. Costa, S. O. Kepler, D. E. Winget, M. S. O'Brien, S. D. Kawaler, A. F. M. Costa, O. Giovannini, A. Kanaan, A. S. Mukadam, F. Mullally, A. Nitta, J. L. Provençal, H. Shipman, M. A. Wood, T. J. Ahrens, A. Grauer, M. Kilic, P. A. Bradley, K. Sekiguchi, R. Crowe, X. J. Jiang, D. Sullivan, T. Sullivan, R. Rosen, J. C. Clemens, R. Janulis, D. O'Donoghue, W. Ogloza, A. Baran, R. Silvotti, S. Marinoni, G. Vauclair, N. Dolez, M. Chevreton, S. Dreizler, S. Schuh, J. Deetjen, T. Nagel, J.-E. Solheim, J. M. Gonzalez Perez, A. Ulla, M. Barstow, M. Burleigh, S. Good, T. S. Metcalfe, S.-L. Kim, H. Lee, A. Sergeev, M. C. Akan, Ö. Çakrl, M. Paparo, G. Viraghalmy, B. N. Ashoka, G. Handler, Ö. Hürkal, F. Johannessen, S. J. Kleinman, R. Kalytis, J. Krzesinski, E. Klumpe, J. Larrison, T. Lawrence, E. Meitas, P. Martinez, R. E. Nather, J.-N. Fu, E. Paktien, R. Rosen, E. Romero-Colmenero, R. Riddle, S. Seetha, N. M. Silvestri, M. Vukovi, B. Warner, S. Zola, L. G. Althaus, A. H. Córsico and M. H. Montgomery A&A 477 (2) 627-640 (2008) DOI: 10.1051/0004-6361:20053470.|
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|Deposited By:||Tony Diaz|
|Deposited On:||28 Sep 2009 22:27|
|Last Modified:||26 Dec 2012 11:25|
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