Now showing items 1-20 of 28

    • Asteroseismological study of massive ZZ Ceti stars with fully evolutionary models 

      Romero, Alejandra Daniela; Kepler, Souza Oliveira; Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Fraga, Luciano (2013) [Journal article]
      We present the first asteroseismological study for 42 massive ZZ Ceti stars based on a large set of fully evolutionary carbon–oxygen core DA white dwarf models characterized by a detailed and consistent chemical inner ...
    • Asteroseismology of ZZ Ceti stars with full evolutionary white dwarf models : II. The impact of AGB thermal pulses on the asteroseismic inferences of ZZ Ceti stars 

      De Gerónimo, Francisco Cesar; Althaus, Leandro Gabriel; Córsico, Alejandro Hugo; Romero, Alejandra Daniela; Kepler, Souza Oliveira (2018) [Journal article]
      Context. The thermally pulsing phase on the asymptotic giant branch (TP-AGB) is the last nuclear burning phase experienced by most low- and intermediate-mass stars. During this phase, the outer chemical stratification above ...
    • Asteroseismology of ZZ Ceti stars with fully evolutionary white dwarf models : I. the impact of the uncertainties from prior evolution on the period spectrum 

      De Gerónimo, Francisco Cesar; Althaus, Leandro Gabriel; Córsico, Alejandro Hugo; Romero, Alejandra Daniela; Kepler, Souza Oliveira (2017) [Journal article]
      Context. ZZ Ceti stars are pulsating white dwarfs with a carbon-oxygen core build up during the core helium burning and thermally pulsing Asymptotic Giant Branch phases. Through the interpretation of their pulsation periods ...
    • A comparative analysis of the observed white dwarf cooling sequence from globular clusters 

      Campos, Fabíola; Bergeron, Pierre; Romero, Alejandra Daniela; Kepler, Souza Oliveira; Ourique, Gustavo; Costa, Jose Eduardo da Silveira; Bonatto, Charles Jose; Winget, Donald Earl; Montgomery, Michael Houston; Pacheco, Thayse Adineia; Bedin, Luigi R. (2016) [Journal article]
      We report our study of features at the observed red end of the white dwarf cooling sequences for three Galactic globular clusters: NGC 6397, 47 Tucanae and M 4. We use deep colour– magnitude diagrams constructed from ...
    • Comparing the asteroseismic properties of pulsating extremely low-mass pre-white dwarf stars and δ Scuti stars 

      Sánchez Arias, J. P.; Córsico, Alejandro Hugo; Romero, Alejandra Daniela; Althaus, Leandro Gabriel (2017) [Journal article]
      We present the first results of a detailed comparison between the pulsation properties of pulsating Extremely Low-Mass pre-white dwarf stars (the pre-ELMV variable stars) and δ Scuti stars. The instability domains of these ...
    • Comparing the asteroseismic properties of pulsating pre-extremely low mass white dwarf and δ Scuti stars 

      Sánchez Arias, J. P.; Romero, Alejandra Daniela; Córsico, Alejandro Hugo; Pelisoli, Ingrid Domingos; Antoci, Victoria L.; Kepler, Souza Oliveira; Althaus, Leandro Gabriel; Corti, Mariela Alejandra (2018) [Journal article]
      Context. Pulsating extremely low-mass pre-white dwarf stars (pre-ELMV), with masses between ~0.15 M⊙ and ~0.30 M⊙, constitute a new class of variable stars showing g- and possibly p-mode pulsations with periods between 320 ...
    • Evidence from K2 for Rapid Rotation in the Descendant of an Intermediate-mass Star 

      Hermes, James J.; Kawaler, Steven D.; Romero, Alejandra Daniela; Kepler, Souza Oliveira; Tremblay, Pier-Emmanuel; Bell, Keaton; Dunlap, Bart; Montgomery, Michael Houston; Gänsicke, Boris; Clemens, J. Christopher; Dennihy, Erik D.; Redfield, Seth (2017) [Journal article]
      Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate (1.13 ± 0.02 hr) of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up ...
    • Evidence of spectral evolution on the white dwarf sample from the Gaia mission 

      Ourique, Gustavo; Kepler, Souza Oliveira; Romero, Alejandra Daniela; Klippel, Theylor Schumacher; Koester, Detlev (2020) [Journal article]
      Since the Gaia data release 2, several works have been published describing a bifurcation in the observed white dwarf colour−magnitude diagram for GBP−GRP>0. Some possible explanations in the literature include the existence ...
    • Four new massive pulsating white dwarfs including an ultramassive DAV 

      Curd, Brandon; Gianninas, Alexandros; Bell, Keaton; Kilic, Mukremin; Romero, Alejandra Daniela; Allende Prieto, Carlos; Winget, Donald Earl; Winget, K. I. (2017) [Journal article]
      We report the discovery of four massive (M > 0.8M ) ZZ Ceti white dwarfs, including an ultramassive 1.16M star. We obtained ground-based, time series photometry for 13 white dwarfs from the Sloan Digital Sky Survey Data ...
    • Ground-based observation of ZZ Ceti stars and the discovery of four new variables 

      Romero, Alejandra Daniela; Amaral, Larissa Antunes; Klippel, Theylor Schumacher; Sanmartim, David; Fraga, Luciano; Ourique, Gustavo; Pelisoli, Ingrid Domingos; Ramos, Gabriel Lauffer; Kepler, Souza Oliveira; Koester, Detlev (2019) [Journal article]
      We perform ground-based photometric observations of 22 DA white dwarf stars, 10 already known ZZ Cetis and 12 candidates with atmospheric parameters inside the classical instability strip. We report on the discovery of ...
    • 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 ...
    • New evolutionary sequences for hot h-deficient white dwarfs on the basis of a full account of progenitor evolution 

      Althaus, Leandro Gabriel; Panei, Jorge Alejandro; Bertolami, Marcelo Miguel Miller; García-Berro, Enrique; Córsico, Alejandro Hugo; Romero, Alejandra Daniela; Kepler, Souza Oliveira; Rohrmann, R. D. (2009) [Journal article]
      We present full evolutionary calculations appropriate for the study of hot hydrogen-deficient DO white dwarfs, PG 1159 stars, and DB white dwarfs. White dwarf sequences are computed for a wide range of stellar masses and ...
    • New full evolutionary sequences of H- and He-atmosphere massive white dwarf stars using MESA 

      Ramos, Gabriel Lauffer; Romero, Alejandra Daniela; Kepler, Souza Oliveira (2018) [Journal article]
      We explore the evolution of hydrogen-rich and hydrogen-deficient white dwarf stars with masses between 1.012 and 1.307M , and initial metallicity of Z = 0.02. These sequences are the result ofmain-sequence stars with masses ...
    • New white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Koester, Detlev; Ourique, Gustavo; Romero, Alejandra Daniela; Reindl, Nicole; Kleinman, Scot James; Eisenstein, Daniel, J.; Valois, Adeilton Dean Marques; Amaral, Larissa Antunes (2016) [Journal article]
      We report the discovery of 6576 new spectroscopically confirmed white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12. We obtain Teff, log g and mass for hydrogen atmospherewhite dwarf stars (DAs) ...
    • New white dwarf stars in the Sloan Digital Sky Survey Data Release 10 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Koester, Detlev; Ourique, Gustavo; Kleinman, Scot James; Romero, Alejandra Daniela; Nitta, Atsuko; Eisenstein, Daniel, J.; Costa, Jose Eduardo da Silveira; Kulebi, Baybars; Jordan, Stefan; Dufour, Patrick; Giommi, Paolo; Rebassa-Mansergas, Alberto (2015) [Journal article]
      We report the discovery of 9088 new spectroscopically confirmed white dwarfs and subdwarfs in the Sloan Digital Sky Survey Data Release 10. We obtain Teff, log g and mass for hydrogen atmosphere white dwarf stars (DAs) and ...
    • On the evolutionary status and pulsations of the recently discovered blue large-amplitude pulsators (BLAPs) 

      Romero, Alejandra Daniela; Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Pelisoli, Ingrid Domingos; Kepler, Souza Oliveira (2018) [Journal article]
      The blue large-amplitude pulsators (BLAPs) constitute a new class of pulsating stars. They are hot stars with effective temperatures of ~30 000K and surface gravities of log g ~ 4.9, that pulsate with periods in the range ...
    • Probing the structure of Kepler ZZ Ceti stars with full evolutionary models-based asteroseismology 

      Romero, Alejandra Daniela; Córsico, Alejandro Hugo; Castanheira, Bárbara Garcia; De Gerónimo, Francisco Cesar; Kepler, Souza Oliveira; Koester, Detlev; Kawka, Adela; Althaus, Leandro Gabriel; Hermes, James J.; Bonatto, Charles Jose; Gianninas, Alexandros (2017) [Journal article]
      We present an asteroseismological analysis of four ZZ Ceti stars observed with the Kepler spacecraft: GD 1212, SDSS J113655.17+040952.6, KIC 11911480, and KIC 4552982, based on a grid of full evolutionary models of DA white ...
    • Pulsating low-mass white dwarfs in the frame of new evolutionary sequences : VI. Thin H-envelope sequences and asteroseismology of ELMV stars revisited 

      Calcaferro, Leila Magdalena; Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Romero, Alejandra Daniela; Kepler, Souza Oliveira (2018) [Journal article]
      Context. Some low-mass white-dwarf (WD) stars with H atmospheres currently being detected in our galaxy, show long-period g(gravity)-mode pulsations, and comprise the class of pulsating WDs called extremely low-mass variable ...
    • Pulsating white dwarfs 

      Kepler, Souza Oliveira; Romero, Alejandra Daniela (2017) [Journal article]
      The Sloan Digital Sky Survey has allowed us to increase the number of known white dwarfs by a factor of five and consequently the number of known pulsating white dwarfs also by a factor of five. It has also led to the ...
    • Seismology of a massive pulsating hydrogen atmosphere white dwarf 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Antonio, Viviane Peçanha; Costa, Jose Eduardo da Silveira; Fraga, Luciano; Hermes, James J.; Winget, Donald Earl; Castanheira, Bárbara Garcia; Córsico, Alejandro Hugo; Romero, Alejandra Daniela; Althaus, Leandro Gabriel; Kleinman, Scot James; Nitta, Atsuko (2012) [Journal article]
      We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode ...