• The Everchanging Pulsating White Dwarf GD358 

      Solheim, Jan Erik; Kepler, S.O.; Nather, R. Edward; Gonzalez Perez, Jose M.; Johannessen, Frank; Winget, Don E.; Nitta, Atsuko; Kleinman, S. J.; Metcalfe, Travis; Sekiguchi, Kazuhiro; Xiaojun, Jiang; Sullivan, Denis; Sullivan, Tiri; Janulis, Rimvydas; Meistas, Edmund; Kalytis, Romualdas; Krzesinski, Jurek; Ogloza, Waldemar; O’Donoghue, Darragh; Romero-Colmenero, Encarni; Martinez, Peter; Dreizler, Stefan; Deetjen, Jochen; Nagel, Thorsten; Schuh, Sonja L.; Vauclair, Gerard; Ning, Fu Jian; Chevreton, Michel; Kanaan, Antonio; Costa, Jos´e Eduardo; Costa, Alex Fabiano Murillo; Wood, Matt A.; Silvestri, Nicole; Ahrens, T.J.; Jones, Aaron Kyle; Collins, Ansley E.; Boyer, Martha; Mukadam, Anjum; Klumpe, Eric W.; Larrison, Jesse; Kawaler, Steve; Riddle, Reed; Ulla, Ana; Bradley, Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2003-01-23)
      We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent measurements. We also report on 48 hours of time-series photometric observations in Aug 1996. We detected the non-radial g-modes consistent with degree ℓ = 1 and radial ...
    • The pulsation modes of the pre-white dwarf PG 1159-035 

      Costa, J. E. S.; Solheim, Jan Erik; Kepler, S. O.; Winget, D. E.; O’Brien, M. S.; Kawaler, S. D.; Costa, A. F. M.; Giovannini, O.; Kanaan, A.; Mukadam, A. S.; Mullally, F.; Nitta, A.; Provenc, J. L.; Shipman, H.; Wood, M. A.; Ahrens, T. J.; Grauer, A.; Kilic, M.; Bradley, P. A.; Sekiguchi, K.; Crowe, R.; Jiang, X. J.; Sullivan, D.; Sullivan, T.; Rosen, R.; Clemens, J. C.; Janulis, R.; O’Donoghue, D.; Ogloza, W.; Baran, A.; Silvotti, R.; Marinoni, S.; Vauclair, G.; Dolez, N.; Chevreton, M.; Dreizler, S.; Schuh, S.; Deetjen, J.; Nagel, T.; Gonzalez Perez, J. M.; Ulla, A.; Barstow, Martin; Burleigh, M.; Good, S.; Metcalfe, T.S.; Kim, S.-L.; Lee, H.; Sergeev, A.; Akan, M.C.; Çakırlı, Ö.; Paparo, M.; Viraghalmy, G.; Ashoka, B. N.; Handler, G.; Hürkal, Özlem; Johannessen, F.; Kleinman, S. J.; Kalytis, R.; Krzesinski, J.; Klumpe, E.; Larrison, J.; Lawrence, T.; Meištas, E.; Martinez, P.; Nather, R. E.; Fu, J.-N.; Pakštienė, E.; Rosen, R.; Romero-Colmenero, E.; Riddle, R.; Seetha, S.; Silvestri, N. M.; Vučković, M.; Warner, B.; Zola, S.; Althaus, L. G.; Córsico, A. H.; Montgomery, M. H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2008)
      Context. PG 1159-035, a pre-white dwarf with Teff ≃ 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 ...
    • Understanding the Cool DA White Dwarf Pulsator, G29–38 

      Solheim, Jan Erik; Kleinman, S. J.; Bruvold, A.; Nather, R. E.; Winget, D. E.; Clemens, J. C.; Bradley, A.; Kanaan, A.; Claver, C. F.; Watson, T. K.; Yanagida, K.; Nitta, A.; Dixson, J. S.; Grauer, A. D.; Hine, B. P.; Fontaine, G.; Liebert, James; Sullivan, D. J.; Wickramasinghe, D. T.; Achilleos, N.; Mara, T. M. K.; Seetha, S.; Ashoka, B. N.; Leibowitz, E. M.; Moskalik, P.; Krzesi´nski, J.; O’Donoghue, D.; Kurtz, D. W.; Warner, B.; Martinez, Peter; Dolez, N.; Chevreton, M.; Barstow, M. A.; Kepler, S. O.; Giovannini, O.; Hansen, C. J.; Augusteijn, T. (Journal article; Tidsskriftartikkel; Peer reviewed, 1997-10-10)
      The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post main sequence evolution, along with their cooling rates, allowing us to calibrate their ages directly. The most important set of white dwarf variables to ...