Navegação por Assunto "Interior estelar"

Resultados 1-13 de 13

    • Anisotropic emission stellar population and x-ray sources in the seyfert 2 galaxy eso 138 - g01 

      Schmitt, Henrique Roberto; Storchi-Bergmann, Thaisa (1995) [Artigo de periódico]
      We present narrow-band CCD images of the high-excitation Seyfert 2 galaxy ES0138-G01, centred on the emission tines [O III] λ5007, Hα+[N II] λλ6548, 6584 and adjacent continua. The continuum-subtracted [O III] image presents ...

    • Espectros de absorção, contínuo óptico e avermelhamento em núcleos normais e ativos de galáxias espirais 

      Dottori, Horacio Alberto (1983) [Tese]
      Observações fotomítricas em UBV com multidiafragma, e observações espectrofotomítricas da região central das galãxias espirais são apresentadas para NGC 5530, 5643 e 6699, com núcleo normal; NGC 1097, 2997 e 5236, com ...

    • Evidence for temperature change and oblique pulsation from light curve fits of the pulsating white dwarf GD 358 

      Montgomery, Michael Houston; Provencal, Judith L.; Kanaan Neto, Antonio Nemer; Mukadam, Anjum Shagufta; Thompson, S. E.; Dalessio, J.; Shipman, Harry L.; Winget, Donald Earl; Kepler, Souza Oliveira; Koester, Detlev (2010) [Artigo de periódico]
      Convective driving, the mechanism originally proposed by Brickhill for pulsating white dwarf stars, has gained general acceptance as the generic linear instability mechanism in DAV and DBV white dwarfs. This physical ...

    • Evidence of thin helium envelopes in PG 1159 stars 

      Althaus, Leandro Gabriel; Córsico, Alejandro Hugo; Bertolami, Marcelo Miguel Miller; García-Berro, Enrique; Kepler, Souza Oliveira (2008) [Artigo de periódico]
      We present evidence that PG 1159 stars could harbor He-rich envelopes substantially thinner than those predicted by current evolutionary models with current estimates of mass loss, which may be attributable to an extensive ...

    • Galaxy properties in different environments. II. Star formation in bulges of late-type spirals 

      Bica, Eduardo Luiz Damiani; Maia, Marcio Antonio Geimba; Bonatto, Charles Jose; Dottori, Horacio Alberto; Pastoriza, Miriani Griselda (1994) [Artigo de periódico]
      The star formation history in the nucleus of late spiral galaxies is compared between a sample in a high galaxy density medium (HDS) and a control sample (CS) of isolated galaxies. We have observed 20 HDS and 18 CS galaxies ...

    • HST observations of the pulsating white dwarf GD 358 

      Castanheira, Bárbara Garcia; Nitta, Atsuko; Kepler, Souza Oliveira; Winget, Donald Earl; Koester, Detlev (2005) [Artigo de periódico]
      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 ...

    • 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) [Artigo de periódico]
      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 ...

    • Probing the internal rotation of pre-white dwarf stars with asteroseismology : the case of PG 0122+200 

      Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Kawaler, Steven D.; Bertolami, Marcelo Miguel Miller; García-Berro, Enrique; Kepler, Souza Oliveira (2011) [Artigo de periódico]
      We put asteroseismological constraints on the internal rotation profile of theGWVir (PG1159- type) star PG 0122+200. To this end we employ a state-of-the-art asteroseismological model for this star and assess the expected ...

    • Spectroscopy monitoring of active galactic nuclei from CTIO. I. NGC 3227 

      Winge, Claudia; Peterson, Bradley M.; Horne, Keith; Pogge, Richard William; Pastoriza, Miriani Griselda; Storchi-Bergmann, Thaisa (1995) [Artigo de periódico]
      The results of a five-month monitoring campaign on the Seyfert 1.5 galaxy NGC 3227 are presented. Variability was detected in the continuum and in the broad emission lines. Cross correlations of the 4200 Å continuum light ...

    • The pulsation modes of the pre-white dwarf PG 1159-035 

      Costa, Jose Eduardo da Silveira; Kepler, Souza Oliveira; Winget, Donald Earl; O'Brien, M. Sean; Kawaler, Steven D.; Costa, Alex Fabiano Murillo da; Giovannini Junior, Odilon; Kanaan Neto, Antonio Nemer; Mukadam, Anjum Shagufta; Mullally, Fergal; Nitta, Atsuko; Provencal, Judith L.; Shipman, Harry L.; Wood, Matthew A.; Ahrens, T.J.; Grauer, Albert D.; Kilic, Mukremin; Bradley, Paul A.; Sekiguchi, Kazuhiro; Crowe, Richard A.; Jiang, Xiaojun; Sullivan, Denis J.; Sullivan, Terry; Rosen, Rachel; Clemens, J. Christopher; Janulis, Rimvydas; O'Donoghue, Darragh; Ogloza, Waldemar; Baran, Andrzej; Silvotti, Roberto; Marinoni, S.; Vauclair, Gérard; Dolez, Noël; Chevreton, Michel; Dreizler, Stefan; Schuh, Sonja L.; Deetjen, Jochen L.; Nagel, Thorsten; Solheim, Jan-Eric; Gonzalez Perez, Jose Miguel; Ulla, Ana; Barstow, Martin A.; Burleigh, Matt; Good, Simon A.; Metcalfe, Travis S.; Kim, Seung-Lee; Lee, H.; Sergeev, A.; Akan, Mustafa Can; Cakirli, Ö; Paparo, Margit; Virághalmy, Géza; Ashoka, B.N.; Handler, Gerald; Hürkal, Özlem; Johannessen, F.; Kleinman, Scot James; Kalytis, Romualdas; Krzesinski, Jerzy; Klumpe, Eric W.; Larrison, Jesse; Lawrence, T.; Meistas, Edmundas G.; Martinez, Peter; Nather, R. Edward; Fu, Jianning Ning; Pakstiene, Erika; Rosen, R.; Romero-Colmenero, Encarni; Riddle, Reed L.; Seetha, S.; Silvestri, Nicole M.; Vuckovic, Maja; Warner, B.; Zola, Staszek; Althaus, Leandro Gabriel; Córsico, Alejandro Hugo; Montgomery, Michael Houston (2008) [Artigo de periódico]
      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 ...

    • The rate of cooling of the pulsating white dwarf star G117−B15A : a new asteroseismological inference of the axion mass 

      Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Bertolami, Marcelo Miguel Miller; Romero, Alejandra Daniela; García-Berro, Enrique; Isern, J.; Kepler, Souza Oliveira (2012) [Artigo de periódico]

    • Toward ensemble asteroseismology of ZZ Ceti stars with fully evolutionary models 

      Romero, Alejandra Daniela; Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Kepler, Souza Oliveira; Castanheira, Bárbara Garcia; Bertolami, Marcelo Miguel Miller (2012) [Artigo de periódico]
      ZZ Ceti stars form the most numerous group of degenerate variable stars. They are otherwise normal DA (H-rich atmospheres) white dwarfs that exhibit pulsations. Here, we present an asteroseismological analysis for 44 bright ...

    • Whole Earth Telescope observations of BPM 37093 : a seismological test of crystallization theory in white dwarfs 

      Kanaan Neto, Antonio Nemer; Nitta, Atsuko; Winget, Donald Earl; Kepler, Souza Oliveira; Montgomery, Michael Houston; Metcalfe, Travis S.; Oliveira, H.; Fraga, Luciano; Costa, Alex Fabiano Murillo da; Costa, Jose Eduardo da Silveira; Castanheira, Bárbara Garcia; Giovannini Junior, Odilon; Nather, R. Edward; Mukadam, Anjum Shagufta; Kawaler, Steven D.; O'Brien, M. Sean; Reed, M. D.; Kleinman, Scot James; Provencal, Judith L.; Watson, Todd K.; Kilkenny, Dave; Sullivan, Denis J.; Sullivan, Terry; Shobbrook, Bob; Jiang, Xiaojun; Ashoka, B.N.; Seetha, S.; Leibowitz, Elia M.; Ibbetson, Peter A.; Mendelson, Haim; Meistas, Edmundas G.; Kalytis, Romualdas; Alisauskas, Darius; O'Donoghue, Darragh; Buckley, David A.H.; Martinez, Peter; Van Wyk, Francois; Stobie, Robert S.; Marang, Fred; Van Zyl, L.; Ogloza, Waldemar; Krzesinski, Jerzy; Zola, Staszek; Moskalik, Pawel; Breger, M.; Stankov, A.; Silvotti, Roberto; Piccioni, Adalberto; Vauclair, Gérard; Dolez, Noël; Chevreton, Michel; Deetjen, Jochen L.; Dreizler, Stefan; Schuh, Sonja L.; Gonzalez Perez, Jose Miguel; Ostensen, Roy; Ulla, Ana; Manteiga, Minia; Suarez, Olga; Burleigh, Matt; Barstow, Martin A. (2005) [Artigo de periódico]
      BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (~1.1 Mʘ) to theoretically crystallize while still inside the ZZ Ceti instability strip (Teff ~ 12 000 K). As a consequence, ...