Navegação Ciências Exatas e da Terra por Assunto "Stars: fundamental parameters"

Resultados 1-20 de 22

    • 18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging 

      Meléndez, Jorge; Ramírez, Iván; Karakas, Amanda I.; Yong, David; Monroe, TalaWanda Rose; Bedell, Megan; Bergemann, Maria; Asplund, Martin; Maia, Marcelo Tucci; Bean, Jacob L.; Nascimento Júnior, José Dias do; Bazot, Michael; Alves-Brito, Alan; Freitas, Fabrício Catani de; Castro, Matthieu Sébastien (2014) [Artigo de periódico]
      We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), ...

    • Accurate atmospheric parameters at moderate resolution using spectral indices : preliminary application to the MARVELS survey 

      Ghezzi, Luan; Ferreira, Letícia D.; Lorenzo-Oliveira, Diego; Mello, Gustavo Frederico Porto de; Santiago, Basilio Xavier; De Lee, Nathan M.; Lee, Brian L.; Costa, Luiz N. da; Maia, Marcio Antonio Geimba; Ogando, Ricardo L.C.; Wisniewski, J.P.; González Hernández, Jonay I.; Stassun, Keivan G.; Fleming, S.W.; Schneider, D.P.; Mahadevan, Suvrath; Cargile, Phillip A.; Ge, Jian; Pepper, J.; Wang, Ji; Paegert, Martin (2014) [Artigo de periódico]
      Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature Teff, metallicity [Fe/H], and surface gravity log g) for ...

    • 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 ...

    • Bayesian distances and extinctions for giants observed by Kepler and APOGEE 

      Rodrigues, Thaise da Silva; Girardi, Leo Alberto; Miglio, Andrea; Bossini, Diego; Bovy, Jo; Epstein, Courtney; Pinsonneault, Marc H.; Zasowski, G.; Allende Prieto, Carlos; Chaplin, William James; Hekker, Saskia; Johnson, J.A.; Mészáros, S.; Mosser, Benoît; Anders, Friedrich; Basu, Sarbani; Beers, T.C.; Chiappini, C.C.M.; Costa, Luiz N. da; Elsworth, Yvonne P.; Garcia, Rafael A.; García Pérez, Ana Elia; Maia, Marcio Antonio Geimba; Majewski, Steven Raymond; Mathur, Savita; Montalbán, Josefina; Nidever, D.L.; Santiago, Basilio Xavier; Schultheis, Mathias; Serenelli, Aldo M.; Shetrone, M. (2014) [Artigo de periódico]
      We present a first determination of distances and extinctions for individual stars in the first release of the APOKASC catalogue, built from the joint efforts of the Apache Point Observatory Galactic Evolution Experiment ...

    • Bpm 24754 : a new southern zz ceti star 

      Giovannini Junior, Odilon; Kepler, Souza Oliveira; Kanaan Neto, Antonio Nemer; Costa, A.F.M.; Koester, Detlev (1998) [Artigo de periódico]
      We report the discovery of a new long{period ZZ Ceti star through the analysis of photometric time series gathered on 7 nights between 1995 and 1996. The light curve displays a periodic variation with a period of ~ 18 min ...

    • Carbon, isotopic ratio 12C/13C, and nitrogen in solar twins : constraints for the chemical evolution of the local disc 

      Botelho, Rafael Bueno; Milone, André de Castro; Meléndez, Jorge; Alves-Brito, Alan; Spina, Lorenzo; Bean, Jacob L. (2020) [Artigo de periódico]
      Abundances of light elements in dwarf stars of different ages are important constraints for stellar yields, Galactic chemical evolution and exoplanet chemical composition studies. We have measured C and N abundances and ...

    • Galactic archaeology with asteroseismology and spectroscopy : red giants observed by CoRoT and APOGEE 

      Anders, Friedrich; Santiago, Basilio Xavier; Zasowski, G. (2017) [Artigo de periódico]
      With the advent of the space missions CoRoT and Kepler, it has recently become feasible to determine precise asteroseismic masses and relative ages for large samples of red giant stars. We present the CoRoGEE dataset, ...

    • J-PLUS : identification of low-metallicity stars with artificial neural networks using SPHINX 

      Whitten, Devin; Chies-Santos, Ana Leonor; Vázquez Ramió, Héctor (2019) [Artigo de periódico]
      Context. We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method ...

    • New hydrogen-deficient (pre-) white dwarfs in the Sloan Digital Sky Survey Data Release 10 

      Werner, Klaus; Rauch, Thomas; Kepler, Souza Oliveira (2014) [Artigo de periódico]
      We have detected 21 new, very hot hydrogen-deficient (pre-) white dwarfs (spectral types O(He), hot DO, PG1159) in the Data Release 10 of the Sloan Digital Sky Survey. We present the results of non-local thermodynamic ...

    • 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 ...

    • Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 

      Anders, Friedrich; Santiago, Basilio Xavier; Enke, Harry (2019) [Artigo de periódico]
      Combining the precise parallaxes and optical photometry delivered by Gaia’s second data release with the photometric catalogues of Pan-STARRS1, 2MASS, and AllWISE, we derived Bayesian stellar parameters, distances, and ...

    • 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) [Artigo de periódico]
      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 ...

    • Spectroscopic binaries in the Solar Twin Planet Search program : from substellar–mass to M dwarf companions 

      Santos, Leonardo Augusto Gonçalves dos; Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Spina, Lorenzo; Alves-Brito, Alan; Dreizler, Stefan; Ramírez, Iván; Asplund, Martin (2017) [Artigo de periódico]
      Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do ...

    • StarHorse : a Bayesian tool for determining stellar masses, ages, distances, and extinctions for field stars 

      Queiroz, Anna Bárbara de Andrade; Anders, Friedrich; Santiago, Basilio Xavier; Chiappini, C.C.M.; Steinmetz, M.; Dal Ponte, Marina; Stassun, Keivan G.; Costa, Luiz N. da; Maia, Marcio Antonio Geimba; Souza, Juliana Crestani Ribeiro de; Beers, T.C.; Fernández-Trincado, José Gregorio; García-Hernández, D. A.; Roman-Lopes, Alexandre; Zamora, Olga (2018) [Artigo de periódico]
      Understanding the formation and evolution of our Galaxy requires accurate distances, ages, and chemistry for large populations of field stars. Here, we present several updates to our spectrophotometric distance code, which ...

    • The solar twin planet search I. Fundamental parameters of the stellar sample 

      Ramírez, Iván; Meléndez, Jorge; Bean, Jacob L.; Asplund, Martin; Bedell, Megan; Monroe, TalaWanda Rose; Casagrande, Luca; Schirbel, Lucas Alexandre; Dreizler, Stefan; Teske, Johanna K.; Maia, Marcelo Tucci; Alves-Brito, Alan; Baumann, P. (2014) [Artigo de periódico]
      Context. We are carrying out a search for planets around a sample of solar twin stars using the HARPS spectrograph. The goal of this project is to exploit the advantage offered by solar twins to obtain chemical abundances ...

    • The solar twin planet search : IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars 

      Santos, Leonardo Augusto Gonçalves dos; Meléndez, Jorge; Nascimento Júnior, José Dias do; Bedell, Megan; Ramírez, Iván; Bean, Jacob L.; Asplund, Martin; Spina, Lorenzo; Dreizler, Stefan; Alves-Brito, Alan; Casagrande, Luca (2016) [Artigo de periódico]
      Context. It is still unclear how common the Sun is when compared to other similar stars in regards to some of its physical properties, such as rotation. Considering that gyrochronology relations are widely used today to ...

    • The solar twin planet search : the age-chromospheric activity relation 

      Lorenzo-Oliveira, Diego; Freitas, Fabrício Catani de; Meléndez, Jorge; Bedell, Megan; Ramírez, Iván; Bean, Jacob L.; Asplund, Martin; Spina, Lorenzo; Dreizler, Stefan; Alves-Brito, Alan; Casagrande, Luca (2018) [Artigo de periódico]
      Context. It is well known that the magnetic activity of solar-type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1–2 Gyr ...

    • Thorium in solar twins : implications for habitability in rocky planets 

      Botelho, Rafael Bueno; Milone, André de Castro; Meléndez, Jorge; Bedell, Megan; Spina, Lorenzo; Asplund, Martin; Santos, Leonardo Augusto Gonçalves dos; Bean, Jacob L.; Ramírez, Iván; Yong, David; Dreizler, Stefan; Alves-Brito, Alan; Galarza, Jhon Joel Yana (2019) [Artigo de periódico]
      We have investigated the thorium (Th) abundance in a sample of 53 thin disc solar twins covering a wide range of ages. These data provide constrains on the mantle energy budget of terrestrial planets that can be formed ...

    • V, J, H and K imaging of the metal rich globular cluster NGC 6528 : reddening, metallicity, and distance based on cleaned colour-magnitude diagrams 

      Momany, Yazan; Ortolani, Sergio; Held, Enrico V.; Barbuy, Beatriz; Bica, Eduardo Luiz Damiani; Renzini, Alvio; Bedin, Luigi R.; Rich, Robert Michael; Marconi, Gianni (2003) [Artigo de periódico]
      New near-infrared observations of NGC6528 are presented. The JHKs observations complement a previous HST/NICMOS data set by Ortolani et al. (2001), in that they sample a larger area, contain a more numerous sample of red ...

    • White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Koester, Detlev; Reindl, Nicole; Geier, Stephan; Romero, Alejandra Daniela; Ourique, Gustavo; Oliveira, Cristiane de Paula; Amaral, Larissa Antunes (2019) [Artigo de periódico]
      White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs provide insight into the early ages of ...