Search results for "Stars : emission-line"

showing 3 items of 3 documents

Pulsating B and Be stars in the Small Magellanic Cloud

2008

Context: Stellar pulsations in main-sequence B-type stars are driven by the kappa-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low metallicities. As the metallicity of the SMC is lower than Z=0.005, it constitutes a very suitable object to test these predictions. Aims: The main objective is to investigate the existence of B-type pulsators at low metallicities, searching for short-term periodic variability in absorption-line B and Be stars in the SMC. The analysis has been performed in a sample of 313 B and Be stars with fundamental astrophysical parameters accurately determined from high-res…

oscillations [stars]statistics [Stars]Be starHertzsprung–Russell diagramMetallicityFOS: Physical sciencesAstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysics01 natural sciencesStars : emission-line Be; stars : oscillations; Stars : early-type; Stars : statistics; Galaxies : Magellanic Cloudssymbols.namesakeMagellanic Clouds [Galaxies]early-type [Stars]0103 physical sciencesAstrophysics::Solar and Stellar Astrophysics010303 astronomy & astrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::GalaxiasAstrophysics::Galaxy AstrophysicsPhysics010308 nuclear & particles physicsAstrophysics (astro-ph)Astronomy and AstrophysicsLight curveGalaxy:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Galaxias [UNESCO]Stars13. Climate actionSpace and Planetary Scienceemission-line Be [Stars]symbolsSmall Magellanic CloudAstrophysics::Earth and Planetary AstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::EstrellasInstability strip:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Estrellas [UNESCO]
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Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54

2008

Context. The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pul- sations have not been detected in the time range 10−3–103 s. A cyclotron line at ∼30 keV has been suggested by various authors but never detected with significance. The stellar wind of the optical companion is abnormally slow. The orbital period, initially reported to be 9.6 days, disappeared and a new periodicity of 19.25 days emerged. Aims. The main objective of our RXTE monitoring of 4U 2206+54 is to study the X-ray orbital variability of the spectral and timing parameters. The new long and uninterrupted RXTE observations allow us to search for long (∼1 h) puls…

media_common.quotation_subjectAstrophysics::High Energy Astrophysical Phenomenapulsars : general [Stars]X-ray binaryFOS: Physical sciencesOrbital eccentricityAstrophysicsAstrophysicsStars : early-type; Stars : emission-line Be; Stars : binaries : close; X-rays : binaries; Stars : pulsars : generalLuminosityearly-type [Stars]:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Fuentes de Rayos X [UNESCO]UNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Fuentes de Rayos XAstrophysics::Solar and Stellar AstrophysicsEccentricity (behavior)binaries : close [Stars]media_commonLine (formation)PhysicsAstrophysics (astro-ph)Astronomy and AstrophysicsOrbital periodLight curveNeutron starSpace and Planetary Scienceemission-line Be [Stars]binaries [X-rays]Astrophysics::Earth and Planetary AstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Estrellas:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Estrellas [UNESCO]
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A photometric study of Be stars located in the seismology fields of COROT

2007

Context: In preparation for the COROT mission, an exhaustive photometric study of Be stars located in the seismology fields of the COROT mission has been performed. The very precise and long-time-spanned photometric observations gathered by the COROT satellite will give important clues of the origin of the Be phenomenon. Aims: The aim of this work is to find short-period variable Be stars located in the seismology fields of COROT and to study and characterise their pulsational properties. Methods: Light curves obtained at the Observatorio de Sierra Nevada together with data from Hipparcos and ASAS-3 of a total of 84 Be stars have been analysed in order to search for short-term variations. W…

statistics [Stars]:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Otras [UNESCO]FOS: Physical sciencesoscillations (including pulsations) [Stars]Context (language use)AstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysics01 natural sciences0103 physical sciencesUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::OtrasAstrophysics::Solar and Stellar Astrophysics010303 astronomy & astrophysicsAstrophysics::Galaxy AstrophysicsPhysics010308 nuclear & particles physicsphotometric [Techniques]Astrophysics (astro-ph)Astronomy and AstrophysicsLight curveStars : emission-line Be; Stars : oscillations (including pulsations); Stars : statistics; Techniques : photometricStarsemission-line Be [Stars]Space and Planetary ScienceSatelliteAstrophysics::Earth and Planetary AstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::EstrellasSeismology:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Estrellas [UNESCO]
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