Now showing items 1-14 of 14

    • 2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV 

      Provencal, Judith L.; Montgomery, Michael Houston; Kanaan Neto, Antonio Nemer; Shipman, Harry L.; Childers, D.; Baran, Andrzej; Kepler, Souza Oliveira; Reed, M. D.; Zhou, Ai-Ying; Eggen, J.; Watson, Todd K.; Winget, Donald Earl; Thompson, S. E.; Riaz, B.; Nitta, Atsuko; Kleinman, Scot James; Crowe, Richard A.; Slivkoff, Jay; Sherard, P.; Purves, Norman G.; Binder, Philippe M.; Knight, R.; Kim, Seung-Lee; Chen, Wen-Ping; Yang, M.; Lin, Hung-Chin; Lin, Chien-Cheng; Chen, C.-W.; Jiang, Xiaojun; Sergeev, A.; Mkrtichian, David; Andreev, M.; Janulis, Rimvydas; Siwak, Michal; Zola, Staszek; Koziel-Wierzbowska, Dorota; Stachowski, G.; Paparo, Margit; Bognár, Zsófia; Handler, Gerald; Lorenz, Denise; Steininger, Bruno; Beck, Paul; Nagel, Thorsten; Kusterer, D.; Hoffman, A.; Reiff, E.; Kowalski, R.; Vauclair, Gérard; Charpinet, Stéphane; Chevreton, Michel; Solheim, Jan-Eric; Pakstiene, Erika; Fraga, Luciano; Dalessio, J. (2009) [Journal article]
      We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated ...
    • An independent method for determining the age of the universe 

      Winget, Donald Earl; Liebert, James; Horn, H.M. van; Fontaine, Gilles; Nather, R. Edward; Kepler, Souza Oliveira; Lamb, Donald Q.; Hansen, Carl J.; Hasen, C.J. (1987) [Journal article]
      The oldest white dwarf stars in the solar neighborhood are still observable, and their luminosity distribution can be used to determine directly the age of the Galactic disk and, somewhat less directly, the age of the ...
    • Asteroseismology of a star cooled by neutrino emission : the pulsating pre-white dwarf PG 0122+200 

      O'Brien, M. Sean; Vauclair, Gérard; Kawaler, Steven D.; Watson, Todd K.; Winget, Donald Earl; Nather, R. Edward; Montgomery, Michael Houston; Nitta, Atsuko; Kleinman, Scot James; Sullivan, Denis J.; Jiang, Xiaojun; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Bhattacharya, J.; Leibowitz, Elia M.; Hemar, Shirley; Ibbetson, Peter A.; Warner, B.; Van Zyl, L.; Moskalik, Pawel; Zola, Staszek; Pajdosz, Gabriel; Krzesinski, Jerzy; Dolez, Noël; Chevreton, Michel; Solheim, Jan-Eric; Thomassen, T.; Kepler, Souza Oliveira; Giovannini Junior, Odilon; Provencal, Judith L.; Wood, Matthew A.; Clemens, J. Christopher (1998) [Journal article]
      Observation of g-mode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several ...
    • Discovery of three optical open clusters in the Galaxy 

      Bica, Eduardo Luiz Damiani; Bonatto, Charles Jose; Dutra, Carlos Maximiliano (2004) [Journal article]
      We report the discovery of three optical open clusters in the Milky Way. Two clusters are in Scutum (Cluster 1 at = 18.44° and b = −0.42°, and Cluster 2 at l= 19.60° and b = −1.02°), thus projected not far from the Galactic ...
    • 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 ...
    • Intrinsic colors of stars in the near-infrared 

      Ducati, Jorge Ricardo; Bevilacqua, Claudio Miguel; Rembold, Sandro Barboza; Ribeiro, Daiana (2001) [Journal article]
      Intrinsic infrared colors of stars in the Johnson 11 color system are derived. The database is a list of 3946 stars with observations in UBV RIJHKLMN, of all spectral types and luminosity classes, including carbon, T Tauri, ...
    • Mass segregation in young compact clusters in the Large Magellanic Cloud - III. Implications for the initial mass function 

      Grijs, Richard de; Gilmore, Gerard Fitzgerald; Mackey, Alasdair Dougal; Wilkinson, Mark I.; Beaulieu, Sylvie F.; Johnson, Rachel A.; Santiago, Basilio Xavier (2002) [Journal article]
      The distribution of core radii of rich clusters in the Large Magellanic Cloud (LMC) systematically increases in both upper limit and spread with increasing cluster age. Cluster-to-cluster variations in the stellar initial ...
    • Measuring the evolutionay rate of cooling of ZZ Ceti 

      Mukadam, Anjum Shagufta; Bischoff-Kim, Agnès; Fraser, Oliver; Córsico, Alejandro Hugo; Montgomery, Michael Houston; Kepler, Souza Oliveira; Romero, Alejandra Daniela; Kronberg, M. E.; Winget, K. I.; Falcon, Ross E.; Chandler, Dean W.; Kuehne, J. W.; Sullivan, Denis J.; Reaves, David Earl; Von Hippel, Theodore A.; Mullally, Fergal; Shipman, Harry L.; Thompson, S. E.; Silvestri, Nicole M.; Hynes, R. I. (2013) [Journal article]
      We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series ...
    • NGC 2180 : a disrupting open cluster? 

      Bonatto, Charles Jose; Bica, Eduardo Luiz Damiani; Pavani, Daniela Borges (2004) [Journal article]
      The spatial dependence of luminosity and mass functions of evolved open clusters is discussed in this work using J and H 2MASS photometry, which allows a wide spatial coverage and proper background determination. The target ...
    • Properties of young star cluster systems : the age signature from near-infrared integrated colours 

      Santos Junior, Joao Francisco Coelho dos; Dottori, Horacio Alberto; Grosbol, Preben (2013) [Journal article]
      Context. A recent JHKs study of several grand-design spiral galaxies, including NGC 2997, shows a bimodal distribution of their system of star clusters and star forming complexes in colour-magnitude and colour-colour ...
    • SN 1992A : ultraviolet and optical studies based on HST, IUE and CTIO observations 

      Kirshner, Robert P.; Jeffery, David J.; Leibundgut, Bruno; Challis, Peter M.; Sonneborn, George; Phillips, M.M.; Suntzeff, N.B.; Smith, Robert Christopher; Winkler, P. Frank; Winge, Claudia; Hamuy, Mario; Hunter, Deidre A.; Roth, Katherine C.; Blades, J.C.; Branch, David; Chevalier, Roger A.; Fransson, Claes; Panagia, Nino; Wagoner, Robert V.; Wheeler, J. Craig; Harkness, Robert P. (1993) [Journal article]
      The Type Ia supernova SN 1992A in the SO galaxy NGC 1380 was observed as a target of opportunity by the International Ultraviolet Explorer (IUE) and with great alacrity by the Hubble Space Telescope (HST). Here we present ...
    • Stellar luminosity functions of rich star clusters in the Large Magellanic Cloud 

      Santiago, Basilio Xavier; Beaulieu, Sylvie F.; Johnson, Rachel A.; Gilmore, Gerard Fitzgerald (2001) [Journal article]
      We show the results of deep V and I HST photometry of 6 rich star clusters in the Large Magellanic Cloud with di erent ages and metallicities. The number of stars with measured magnitudes in each cluster varies from about ...
    • Whole Earth Telescope observations and seismological analysis of the pre-white dwarf pg 2131+066 

      Kawaler, Steven D.; O'Brien, M. Sean; Clemens, J. Christopher; Nather, R. Edward; Winget, Donald Earl; Watson, Todd K.; Yanagida, K.; Dixson, James S.; Bradley, Paul A.; Wood, Matthew A.; Sullivan, Denis J.; Kleinman, Scot James; Meistas, Edmundas G.; Leibowitz, Elia M.; Moskalik, Pawel; Zola, Staszek; Pajdosz, Y.; Krzesinski, Jerzy; Solheim, Jan-Eric; Bruvold, A.; O'Donoghue, Darragh; Katz, M.; Vauclair, Gérard; Dolez, Noël; Chevreton, Michel; Barstow, Martin A.; Kanaan Neto, Antonio Nemer; Kepler, Souza Oliveira; Giovannini Junior, Odilon; Provencal, Judith L.; Hansen, Carl J. (1995) [Journal article]
      As transition objects between the asymptotic giant branch (AGB) and cooling white dwarfs, the PG 1159 stars are key objects for understanding the late stages of stellar evolution. The pulsations exhibited by many members ...
    • Whole Earth Telescope observations of V471 Tauri : the nature of the white dwarf variations 

      Clemens, J. Christopher; Nather, R. Edward; Winget, Donald Earl; Robinson, E.L.; Wood, Matthew A.; Claver, C.F.; Provencal, Judith L.; Kleinman, Scot James; Bradley, Paul A.; Frueh, M.L.; Grauer, Albert D.; Hine, B.P.; Fontaine, Gilles; Achilleos, Nicholas; Wickramasinghe, D.T.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; O'Donoghue, Darragh; Warner, B.; Kurtz, Donald W.; Martinez, Peter; Vauclair, Gérard; Chevreton, Michel; Barstow, Martin A.; Kanaan Neto, Antonio Nemer; Kepler, Souza Oliveira; Augusteijn, T.; Paradijs, J. van; Hansen, Carl J. (1992) [Journal article]
      We have conducted time-series photometric observations of the binary star V471 Tauri using the Whole Earth Telescope observing network. Our purpose was to determine the mechanism responsible for causing the 555 and 277 s ...