Browsing Exact and Earth Sciences by Author "Tweedy, R.W."

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    • A detection of the evolutionary time scale of the da white dwarf G117-B15A with the Whole Earth Telescope 

      Kepler, Souza Oliveira; Winget, Donald Earl; Nather, R. Edward; Bradley, Paul A.; Grauer, Albert D.; Fontaine, Gilles; Bergeron, Pierre; Vauclair, Gérard; Claver, C.F.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Mazeh, Tsevi; Leibowitz, Elia M.; Dolez, Noël; Chevreton, Michel; Barstow, Martin A.; Clemens, J. Christopher; Kleinman, Scot James; Sansom, A.E.; Tweedy, R.W.; Hine, B.P.; Provencal, Judith L.; Wesemael, F.; Wood, Matthew A.; Brassard, P.; Solheim, Jan-Eric; Emanuelsen, P.-I.; Kanaan Neto, Antonio Nemer; Kepler, Souza Oliveira (1991) [Journal article]
      We have detected the time rate of change for the main pulsation period of the 13,000 K DA white dwarf G117-B15A, using the Whole Earth Telescope (WET). The observed rate of period change, P = (12.0 ± 3.5) x 10- 15 s s - ...

    • The unusual helium variable AM Canum Venaticorum 

      Provencal, Judith L.; Winget, Donald Earl; Nather, R. Edward; Robinson, E.L.; Solheim, Jan-Eric; Clemens, J. Christopher; Bradley, Paul A.; Kleinman, Scot James; Kanaan Neto, Antonio Nemer; Claver, C.F.; Hansen, Carl J.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Leibowitz, Elia M.; Meistas, Edmundas G.; Bruvold, A.; Vauclair, Gérard; Dolez, Noël; Chevreton, Michel; Barstow, Martin A.; Sansom, A.E.; Tweedy, R.W.; Fontaine, Gilles; Bergeron, Pierre; Kepler, Souza Oliveira; Wood, Matthew A.; Grauer, Albert D. (1995) [Journal article]
      The unusual variable star AM CVn has puzzled astronomers for over 40 years. This object, both a photometric and spectroscopic variable, is believed to contain a pair of hydrogen-deficient white dwarfs of extreme mass ratio, ...

    • Whole Earth Telescope observations of the DAV white dwarf G226-29 

      Kepler, Souza Oliveira; Giovannini Junior, Odilon; Wood, Matthew A.; Nather, R. Edward; Winget, Donald Earl; Kanaan Neto, Antonio Nemer; Kleinman, Scot James; Bradley, Paul A.; Provencal, Judith L.; Clemens, J. Christopher; Claver, C.F.; Watson, Todd K.; Yanagida, K.; Krisciunas, K.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Leibowitz, Elia M.; Mendelson, Haim; Mazeh, Tsevi; Moskalik, Pawel; Krzesinski, Jerzy; Pajdosz, Y.; Zola, Staszek; Solheim, Jan-Eric; Emanuelsen, P.-I.; Dolez, Noël; Vauclair, Gérard; Chevreton, Michel; Fremy, J. R.; Barstow, Martin A.; Sansom, A.E.; Tweedy, R.W.; Wickramasinghe, D.T.; Ferrario, Lilia; Sullivan, Denis J.; Peet, A.J. van der; Buckley, David A.H.; Chen, A.-L. (1995) [Journal article]
      We observed G226-29 for 121 hr in 1992 February and confirm the presence of the three previously identified frequencies close to 109 s. We find no evidence of other pulsation periods down to our noise level of about 0.35 ...