Navegação Ciências Exatas e da Terra por Autor "Nitta, Atsuko"

Resultados 1-20 de 33

    • 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) [Artigo de periódico]
      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 ...

    • Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope 

      Handler, Gerald; O'Donoghue, Darragh; Muller, M.; Solheim, Jan-Eric; Gonzalez Perez, Jose Miguel; Johannessen, F.; Paparo, Margit; Szeidl, Bela; Virághalmy, Géza; Silvotti, Roberto; Vauclair, Gérard; Dolez, Noël; Pallier, E.; Chevreton, Michel; Kurtz, Donald W.; Bromage, Gordon E.; Cunha, Margarida S.; Ostensen, Roy; Fraga, Luciano; Kanaan Neto, Antonio Nemer; Amorim, André; Giovannini Junior, Odilon; Kepler, Souza Oliveira; Costa, Alex Fabiano Murillo da; Anderson, R.F.; Wood, Matthew A.; Silvestri, Nicole M.; Klumpe, Eric W.; Carlton, Robert F.; Miller, Hugh Richard; McFarland, John P.; Grauer, Albert D.; Kawaler, Steven D.; Riddle, Reed L.; Reed, M. D.; Nather, R. Edward; Winget, Donald Earl; Hill, J.A.; Metcalfe, Travis S.; Mukadam, Anjum Shagufta; Kilic, Mukremin; Watson, Todd K.; Kleinman, Scot James; Nitta, Atsuko; Guzik, Joyce Ann; Bradley, Paul A.; Sekiguchi, Kazuhiro; Sullivan, Denis J.; Sullivan, Terry; Shobbrook, Robert R.; Jiang, Xiaojun; Birch, P.; Ashoka, B.N.; Seetha, S.; Girish, V.; Joshi, Santosh; Dorokhova, Tatyana N.; Dorokhov, N.I.; Akan, Mustafa Can; Meistas, Edmundas G.; Janulis, Rimvydas; Kalytis, Romualdas; Alisauskas, Darius; Anguma, S.K.; Kalebwe, P.C.; Moskalik, Pawel; Ogloza, Waldemar; Stachowski, G.; Pajdosz, Gabriel; Zola, Staszek (2003) [Artigo de periódico]
      We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these ...

    • 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) [Artigo de periódico]
      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 ...

    • Asteroseismology of RXJ 2117+3412, the hottest pulsating PG 1159 star 

      Vauclair, Gérard; Moskalik, Pawel; Pfeiffer, Ben; Chevreton, Michel; Dolez, Noël; Serre, B.; Kleinman, Scot James; Barstow, Martin A.; Sansom, A.E.; Solheim, Jan-Eric; Belmonte, J.A.; Kawaler, Steven D.; Kepler, Souza Oliveira; Kanaan Neto, Antonio Nemer; Giovannini Junior, Odilon; Winget, Donald Earl; Watson, Todd K.; Nather, R. Edward; Clemens, J. Christopher; Provencal, Judith L.; Dixson, James S.; Yanagida, K.; Nitta, Atsuko; Montgomery, Michael Houston; Klumpe, Eric W.; Bruvold, A.; O'Brien, M. Sean; Hansen, Carl J.; Grauer, Albert D.; Bradley, Paul A.; Wood, Matthew A.; Achilleos, Nicholas; Jiang, Shi Yang; Fu, Jianning Ning; Marar, T.M. Krishnan; Ashoka, B.N.; Meistas, Edmundas G.; Chernyshev, A.V.; Mazeh, Tsevi; Leibowitz, Elia M.; Hemar, Shirley; Krzesinski, Jerzy; Pajdosz, Gabriel; Zola, Staszek (2002) [Artigo de periódico]
      The pulsating PG 1159 planetary nebula central star RXJ 2117+3412 has been observed over three successive seasons of a multisite photometric campaign. The asteroseismological analysis of the data, based on the 37 identified ...

    • Constraining the evolution of ZZ Ceti 

      Mukadam, Anjum Shagufta; Kepler, Souza Oliveira; Winget, Donald Earl; Nather, R. Edward; Kilic, Mukremin; Mullally, Fergal; Von Hippel, Theodore A.; Kleinman, Scot James; Nitta, Atsuko; Guzik, Joyce Ann; Bradley, Paul A.; Matthews, Jaymie M.; Sekiguchi, Kazuhiro; Sullivan, Denis J.; Sullivan, Terry; Shobbrook, Robert R.; Birch, P.; Jiang, Xiaojun; Xu, D.W.; Joshi, Santosh; Ashoka, B.N.; Ibbetson, Peter A.; Leibowitz, Elia M.; Ofek, Eran O.; Meistas, Edmundas G.; Janulis, Rimvydas; Alisauskas, Darius; Kalytis, Romualdas; Handler, Gerald; Kilkenny, Dave; O'Donoghue, Darragh; Kurtz, Donald W.; Muller, M.; Moskalik, Pawel; Ogloza, Waldemar; Zola, Staszek; Krzesinski, Jerzy; Johannessen, F.; Gonzalez Perez, Jose Miguel; Solheim, Jan-Eric; Silvotti, Roberto; Bernabei, S.; Vauclair, Gérard; Dolez, Noël; Fu, Jianning Ning; Chevreton, Michel; Manteiga, Minia; Suarez, Olga; Ulla, Ana; Cunha, Margarida S.; Metcalfe, Travis S.; Kanaan Neto, Antonio Nemer; Fraga, Luciano; Costa, Alex Fabiano Murillo da; Giovannini Junior, Odilon; Fontaine, Gilles; Bergeron, Pierre; O'Brien, M. Sean; Sanwal, Divas; Wood, Matthew A.; Ahrens, T.J.; Silvestri, Nicole M.; Klumpe, Eric W.; Kawaler, Steven D.; Riddle, Reed L.; Reed, M. D.; Watson, Todd K. (2003) [Artigo de periódico]
      We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf ) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the ...

    • 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) [Artigo de periódico]
      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) [Artigo de periódico]
      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) [Artigo de periódico]
      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 ...

    • 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) [Artigo de periódico]
      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) [Artigo de periódico]
      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 ...

    • 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 ...

    • 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) [Artigo de periódico]
      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 ...

    • 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) [Artigo de periódico]
      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 db white dwarf stars from the Sloan Digital Sky Survey 

      Nitta, Atsuko; Kleinman, Scot James; Krzesinski, Jerzy; Kepler, Souza Oliveira; Metcalfe, Travis S.; Mukadam, Anjum Shagufta; Mullally, Fergal; Nather, R. Edward; Sullivan, Denis J.; Thompson, S. E.; Winget, Donald Earl (2009) [Artigo de periódico]
      We are searching for new He atmosphere white dwarf pulsators (DBVs) based on the newly found white dwarf stars from the spectra obtained by the Sloan Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their ...

    • 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) [Artigo de periódico]
      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 ...

    • New whole earth telescope observations of cd-247599 : steps towards delta scuti star seismology 

      Handler, Gerald; Pikall, H.; O'Donoghue, Darragh; Buckley, David A.H.; Vauclair, Gérard; Chevreton, Michel; Giovannini Junior, Odilon; Kepler, Souza Oliveira; Goode, P.R.; Provencal, Judith L.; Wood, Matthew A.; Clemens, J. Christopher; O'Brien, M. Sean; Nather, R. Edward; Winget, Donald Earl; Kleinman, Scot James; Kanaan Neto, Antonio Nemer; Watson, Todd K.; Nitta, Atsuko; Montgomery, Michael Houston; Klumpe, Eric W.; Bradley, Paul A.; Sullivan, Denis J.; Wu, K.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Mahra, H.S.; Bhat, B.C.; Babu, V.C.; Leibowitz, Elia M.; Hemar, Shirley; Ibbetson, Peter A.; Mashal, E.; Meistas, Edmundas G.; Dziembowski, W.A.; Pamyantnykh, A.A.; Moskalik, Pawel; Zola, Staszek; Pajdosz, Gabriel; Krzesinski, Jerzy; Solheim, Jan-Eric; Bard, S.; Massarand, C.M.; Breger, M.; Gelbmann, M.J.; Paunzen, E.; North, P. (1997) [Artigo de periódico]
      92 h of new Whole Earth Telescope observations have been acquired for the δ Scuti star CD -24 7599. All the seven pulsation modes reported by Handler et al. are confirmed. However, significant amplitude variations which ...

    • Normal modes and discovery of high-order cross-frequencies in the DBV white dwarf GD 358 

      Vuille, F.; O'Donoghue, Darragh; Buckley, David A.H.; Massacand, C.N.; Solheim, Jan-Eric; Bard, S.; Vauclair, Gérard; Giovannini Junior, Odilon; Kepler, Souza Oliveira; Kanaan Neto, Antonio Nemer; Provencal, Judith L.; Wood, Matthew A.; Clemens, J. Christopher; Kleinman, Scot James; O'Brien, M. Sean; Nather, R. Edward; Winget, Donald Earl; Nitta, Atsuko; Klumpe, Eric W.; Montgomery, Michael Houston; Watson, Todd K.; Bradley, Paul A.; Sullivan, Denis J.; Wu, K.; Marar, T.M. Krishnan; Seetha, S.; Ashoka, B.N.; Mahra, H.S.; Bhat, B.C.; Babu, V.C.; Leibowitz, Elia M.; Hemar, Shirley; Ibbetson, Peter A.; Mashal, E.; Meistas, Edmundas G.; Moskalik, Pawel; Zola, Staszek; Krzesinski, Jerzy; Pajdosz, Gabriel (2000) [Artigo de periódico]
      We present a detailed mode identification performed on the 1994 Whole Earth Telescope (WET) run on GD 358. The results are compared with that obtained for the same star from the 1990 WET data. The two temporal spectra show ...

    • Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS : III. Asteroseismology of the DBV star GD 358 

      Córsico, Alejandro Hugo; Uzundag, Murat; Kepler, Souza Oliveira; Silvotti, Roberto; Althaus, Leandro Gabriel; Koester, Detlev; Baran, Andrzej; Bell, Keaton; Bischoff-Kim, Agnès; Hermes, James J.; Kawaler, Steven D.; Provencal, Judith L.; Winget, Donald Earl; Montgomery, Michael Houston; Bradley, Paul A.; Kleinman, Scot James; Nitta, Atsuko (2022) [Artigo de periódico]
      Context. The collection of high-quality photometric data by space telescopes, such as the completed Kepler mission and the ongoing TESS program, is revolutionizing the area of white-dwarf asteroseismology. Among the different ...

    • Pushing the ground-based limit : 14-μmag photometric precision with the definitive Whole Earth Telescope asteroseismic data set for the rapidly oscillating Ap star HR 1217 

      Kurtz, Donald W.; Cameron, C.; Cunha, Margarida S.; Dolez, Noël; Vauclair, Gérard; Pallier, E.; Ulla, Ana; Kepler, Souza Oliveira; Costa, Alex Fabiano Murillo da; Kanaan Neto, Antonio Nemer; Fraga, Luciano; Giovannini Junior, Odilon; Wood, Matthew A.; Silvestri, Nicole M.; Kawaler, Steven D.; Riddle, Reed L.; Reed, M. D.; Watson, Todd K.; Metcalfe, Travis S.; Mukadam, Anjum Shagufta; Nather, R. Edward; Winget, Donald Earl; Nitta, Atsuko; Kleinman, Scot James; Guzik, Joyce Ann; Bradley, Paul A.; Matthews, Jaymie M.; Sekiguchi, Kazuhiro; Sullivan, Denis J.; Sullivan, Terry; Shobbrook, Robert R.; Jiang, Xiaojun; Birch, P.; Ashoka, B.N.; Seetha, S.; Girish, V.; Joshi, Santosh; Moskalik, Pawel; Zola, Staszek; O'Donoghue, Darragh; Handler, Gerald; Mueller, M.; Gonzalez Perez, Jose Miguel; Solheim, Jan-Eric; Johannessen, F.; Bigot, L. (2005) [Artigo de periódico]
      HR1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even-and odd-l modes that are distorted by the presence of a strong, global magnetic field. Several recent ...

    • SDSS DR7 white dwarf catalog 

      Kleinman, Scot James; Kepler, Souza Oliveira; Koester, Detlev; Pelisoli, Ingrid Domingos; Antonio, Viviane Peçanha; Nitta, Atsuko; Costa, Jose Eduardo da Silveira; Krzesinski, Jerzy; Dufour, Patrick; Lachapelle, François-René; Bergeron, Pierre; Yip, Ching-Wa; Harris, Hugh C.; Eisenstein, Daniel, J.; Althaus, Leandro Gabriel; Córsico, Alejandro Hugo (2013) [Artigo de periódico]
      We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20,407 white dwarf spectra, representing 19,712 stars, and ...