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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Whole Earth Telescope observations of the hot helium atmosphere pulsating white dwarf EC 20058-5234
Monthly Notices of the Royal Astronomical Society, Volume 387, No. 1, Year 2008
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Description
We present the analysis of a total of 177 h of high-quality optical time-series photometry of the helium atmosphere pulsating white dwarf (DBV) EC 20058-5234. The bulk of the observations (135 h) were obtained during a WET campaign (XCOV15) in 1997 July that featured coordinated observing from four southern observatory sites over an 8-d period. The remaining data (42 h) were obtained in 2004 June at Mt John Observatory in NZ over a one-week observing period. This work significantly extends the discovery observations of this low-amplitude (few per cent) pulsator by increasing the number of detected frequencies from 8 to 18, and employs a simulation procedure to confirm the reality of these frequencies to a high level of significance (1 in 1000). The nature of the observed pulsation spectrum precludes identification of unique pulsation mode properties using any clearly discernable trends. However, we have used a global modelling procedure employing genetic algorithm techniques to identify the n, ℓ values of eight pulsation modes, and thereby obtain asteroseismic measurements of several model parameters, including the stellar mass (0.55 M⊙) and Teff (∼28 200 K). These values are consistent with those derived from published spectral fitting: T eff ∼ 28 400 K and log g ∼ 7.86. We also present persuasive evidence from apparent rotational mode splitting for two of the modes that indicates this compact object is a relatively rapid rotator with a period of 2 h. In direct analogy with the corresponding properties of the hydrogen (DAV) atmosphere pulsators, the stable low-amplitude pulsation behaviour of EC 20058 is entirely consistent with its inferred effective temperature, which indicates it is close to the blue edge of the DBV instability strip. Arguably, our most significant result from this work is the clear demonstration that EC 20058 is a very stable pulsator with several dominant pulsation modes that can be monitored for their long-term stability. © 2008 RAS.
Authors & Co-Authors
Sullivan, Denis J.
New Zealand, Wellington
Victoria University of Wellington
New Zealand, Lake Tekapo
University of Canterbury Mount John Observatory
Metcalfe, Travis S.
United States, Austin
The University of Texas at Austin
United States, Boulder
The Earth and Sun Systems Laboratory
O'Donoghue, Darragh E.
South Africa, Cape Town
South African Astronomical Observatory
Winget, Don Earl
United States, Austin
The University of Texas at Austin
Kilkenny, David
South Africa, Cape Town
South African Astronomical Observatory
South Africa, Bellville
University of the Western Cape
van Wyk, François G.
South Africa, Cape Town
South African Astronomical Observatory
Kanaan, Antonio
Brazil, Florianopolis
Universidade Federal de Santa Catarina
Kepler, Souza Oliveira
Brazil, Porto Alegre
Universidade Federal do Rio Grande do Sul
Nitta, Atsuko
United States, Austin
The University of Texas at Austin
Chile, La Serena
Cerro Tololo Inter American Observatory
United States, Hilo
Gemini Observatory
Kawaler, Steven D.
United States, Ames
Iowa State University
Montgomery, Michael H.
United States, Austin
The University of Texas at Austin
Nather, R. Edward
United States, Austin
The University of Texas at Austin
O'Brien, M. Sean
United States, Ames
Iowa State University
United States, New Haven
Yale University
Bischoff-Kim, A.
United States, Austin
The University of Texas at Austin
Wood, Matt A.
United States, Melbourne
Florida Institute of Technology
Jiang, Xiaojun
China, Beijing
National Astronomical Observatories Chinese Academy of Sciences
Leibowitz, Elia M.
Israel, Tel Aviv-yafo
Tel Aviv University
Ibbetson, P. A.
Israel, Tel Aviv-yafo
Tel Aviv University
Zoła, Stanisław
Poland, Krakow
Uniwersytet Jagielloński
Poland, Krakow
Uniwersytet Pedagogiczny Im. Komisji Edukacji Narodowej
Krzesiński, Jurek
Poland, Krakow
Uniwersytet Pedagogiczny Im. Komisji Edukacji Narodowej
Pajdosz, G.
Poland, Krakow
Uniwersytet Pedagogiczny Im. Komisji Edukacji Narodowej
Vauclair, G.
France, Toulouse
Université Toulouse Iii - Paul Sabatier
Dolez, Noël
France, Toulouse
Université Toulouse Iii - Paul Sabatier
Chevreton, Michel
France, Paris
L'observatoire de Paris
Statistics
Citations: 24
Authors: 24
Affiliations: 19
Identifiers
Doi:
10.1111/j.1365-2966.2008.13074.x
ISSN:
00358711
e-ISSN:
13652966
Research Areas
Genetics And Genomics