Browsing by Author "Castanheira, Bárbara Garcia"

Now showing items 1-20 of 36

    • Analysis of IUE spectra of helium-rich white dwarf stars 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira; Handler, Gerald; Koester, Detlev (2006) [Journal article]
      We studied the class of DB white dwarf stars, using re-calibrated UV spectra for thirty four DBs obtained with the IUE satellite. By comparing the observed energy distributions with model atmospheres, we simultaneously ...

    • Anãs brancas pulsantes 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira (2001) [Abstract published in event]

    • Anãs brancas pulsantes 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira (1999) [Abstract published in event]

    • Anãs brancas pulsantes 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira (2000) [Abstract published in event]

    • Determinação dos modos de pulsação da anã branca pulsante G 185-32 

      Castanheira, Bárbara Garcia (2003) [Dissertation]
      Estrelas anãs brancas são o final evolutivo de quase 98% de todas as estrelas; após a perda de massa durante as fases de gigante e supergigante, elas vão se tornar anãs brancas. Nosso trabalho é estudar a estrutura das ...

    • Discovery of 25 new DAVs 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira (2006) [Complete work published in event]

    • Discovery of an ultramassive pulsating white dwarf 

      Hermes, James J.; Kepler, Souza Oliveira; Castanheira, Bárbara Garcia; Gianninas, Alexandros; Winget, Donald Earl; Montgomery, Michael Houston; Brown, Warren R.; Harrold, Samuel T. (2013) [Journal article]
      We announce the discovery of themostmassive pulsating hydrogen-atmosphere white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 ± 210 K WD with a log g = ...

    • Discovery of eleven new ZZ Ceti stars 

      Reimers, Dieter; Castanheira, Bárbara Garcia; Kepler, Souza Oliveira; Mullally, Fergal; Winget, Donald Earl; Koester, Detlev; Voss, Björn; Kleinman, Scot James; Nitta, Atsuko; Eisenstein, D.J.; Napiwotzki, Ralf (2006) [Journal article]
      We report the discovery of eleven new ZZ Cetis using telescopes at OPD (Observatório do Pico dos Dias/LNA) in Brazil, the 4.1 m SOAR (Southern Astrophysical Research) telescope at Cerro Pachon, Chile, and the 2.1 m Otto ...

    • Discovery of five new massive pulsating white dwarf stars 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira; Kleinman, Scot James; Nitta, Atsuko; Fraga, Luciano (2013) [Journal article]
      Using the SOuthern Astrophysical Research telescope (SOAR) Optical Imager at the SOAR 4.1 m telescope, we report on the discovery of five new massive pulsating white dwarf stars. Our results represent an increase of about ...

    • Discovery of fourteen new ZZ Cetis with SOAR 

      Kepler, Souza Oliveira; Castanheira, Bárbara Garcia; Saraiva, Maria de Fátima Oliveira; Nitta, Atsuko; Kleinman, Scot James; Mullally, Fergal; Winget, Donald Earl; Eisenstein, D.J. (2005) [Journal article]
      We report the discovery of fourteen new ZZ Cetis with the 4.1 m Southern Astrophysical Research telescope, at Cerro Pachon, in Chile. The candidates were selected from the SDSS (Sloan Digital Sky Survey) DA white dwarf ...

    • Discovery of twelve ZZ Ceti stars 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira; Kleinman, Scot James; Nitta, Atsuko; Fraga, Luciano (2009) [Complete work published in event]

    • Eleven new DA white dwarf variable stars from the Sloan Digital Sky Survey 

      Mullally, Fergal; Thompson, S. E.; Castanheira, Bárbara Garcia; Winget, Donald Earl; Kepler, Souza Oliveira; Eisenstein, D.J.; Kleinman, Scot James; Nitta, Atsuko (2005) [Journal article]
      We report the discovery of 11 new variable DAwhite dwarf (ZZ Ceti) stars. Candidates were selected by deriving temperatures from model fits to spectra obtained from the Sloan Digital Sky Survey (SDSS). We also find objects ...

    • Empirical determination of convection parameters in white dwarfs. I. Whole earth telescope obsevations of EC14012-1446 

      Provencal, Judith L.; Montgomery, Michael Houston; Kanaan Neto, Antonio Nemer; Thompson, S. E.; Dalessio, J.; Shipman, Harry L.; Childers, D.; Clemens, J. Christopher; Rosen, Rachel; Henrique, P.; Bischoff-Kim, Agnès; Strickland, Willie; Chandler, Dean W.; Walter, B.; Watson, Todd K.; Castanheira, Bárbara Garcia; Wang, Siqiu; Handler, Gerald; Wood, Matthew A.; Vennes, S.; Nemeth, Peter; Kepler, Souza Oliveira; Reed, M. D.; Nitta, Atsuko; Kleinman, Scot James; Brown, Tim; Kim, Seung-Lee; Sullivan, Denis J.; Chen, Wen-Ping; Yang, M.; Shih, Chia-You; Jiang, Xiaojun; Sergeev, A.; Maksim, A.; Janulis, Rimvydas; Baliyan, Kiran S.; Vats, Hari Om; Zola, Staszek; Baran, Andrzej; Winiarski, M.; Ogloza, Waldemar; Paparo, Margit; Baran, Andrzej; Bognár, Zsófia; Papics, P.; Kilkenny, Dave; Sefako, R.; Buckley, David A.H.; Loaring, N.; Kniazev, A.; Silvotti, Roberto; Galleti, S.; Nagel, Thorsten; Vauclair, Gérard; Dolez, Noël; Fremy, J. R.; Gonzalez Perez, Jose Miguel; Almenara, J. M.; Fraga, Luciano (2012) [Journal article]
      We report on an analysis of 308.3 hr of high-speed photometry targeting the pulsating DA white dwarf EC14012-1446. The datawere acquiredwith theWhole Earth Telescope during the 2008 international observing run XCOV26. The ...

    • Gemini spectra of 12 000 k white dwarf stars 

      Kepler, Souza Oliveira; Castanheira, Bárbara Garcia; Costa, Alex Fabiano Murillo da; Koester, Detlev (2006) [Journal article]
      We report signal-to-noise ratio (S/N) - ~100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8-m Gemini north telescope. These stars have 18 < g < 19 and are around Teff ~ 12 000 ...

    • HST observations of the pulsating white dwarf GD 358 

      Castanheira, Bárbara Garcia; Nitta, Atsuko; Kepler, Souza Oliveira; Winget, Donald Earl; Koester, Detlev (2005) [Journal article]
      We used time-resolved ultraviolet spectroscopy obtained with the FOS and STIS spectrographs of the Hubble Space Telescope (HST), together with archival IUE observations to measure the effective temperature (Teff), surface ...

    • Magnetic white dwarfs in the SDSS and estimating the mean mass of normal DA and DB WDs 

      Kepler, Souza Oliveira; Kleinman, Scot James; Pelisoli, Ingrid Domingos; Antonio, Viviane Peçanha; Diaz, M.P.; Koester, Detlev; Castanheira, Bárbara Garcia; Nitta, Atsuko (2010) [Complete work published in event]

    • Magnetic white dwarf stars in the Sloan Digital Sky Survey 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Jordan, Stefan; Kleinman, Scot James; Koester, Detlev; Kulebi, Baybars; Antonio, Viviane Peçanha; Castanheira, Bárbara Garcia; Nitta, Atsuko; Costa, Jose Eduardo da Silveira; Winget, Donald Earl; Kanaan Neto, Antonio Nemer; Fraga, Luciano (2013) [Journal article]
      To obtain better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for ...

    • Measuring the evolution of the most stable optical clock G 117-B15A 

      Kepler, Souza Oliveira; Costa, Jose Eduardo da Silveira; Castanheira, Bárbara Garcia; Winget, Donald Earl; Mullally, Fergal; Nather, R. Edward; Kilic, Mukremin; Von Hippel, Theodore A.; Mukadam, Anjum Shagufta; Sullivan, Denis J. (2005) [Journal article]
      We report our measurement of the rate of change of period with time (˙P ) for the 215 s periodicity in the pulsating white dwarf G 117-B15A, the most stable optical clock known. After 31 years of observations, we have ...

    • New developments of the ZZ Ceti instability strip : the discovery of 11 new variables 

      Castanheira, Bárbara Garcia; Kepler, Souza Oliveira; Kleinman, Scot James; Nitta, Atsuko; Fraga, Luciano (2010) [Journal article]
      Using the The SOuthern Astrophysical Research (SOAR) 4.1-m telescope, we report on the discovery of low amplitude pulsations for three stars previously reported as not-observed-tovary (NOV) by Mukadam et al. and Mullally ...

    • New pulsating ZZ ceti stars 

      Kepler, Souza Oliveira; Castanheira, Bárbara Garcia (2009) [Complete work published in event]