Search results for "Variable stars"

showing 3 items of 3 documents

Long-term X-ray variability of the microquasar system LS 5039/RX J1826.2−1450

2003

We report on the results of the spectral and timing analysis of a BeppoSAX observation of the microquasar system LS 5039/RX J1826.2-1450. The source was found in a low-flux state with Fx(1-10 keV)= 4.7 x 10^{-12} erg cm^{-2} s^{-1}, which represents almost one order of magnitude lower than a previous RXTE observation 2.5 years before. The 0.1--10 keV spectrum is described by an absorbed power-law continuum with photon-number spectral index Gamma=1.8+-0.2 and hydrogen column density of NH=1.0^{+0.4}_{-0.3} x 10^{22} cm^{-2}. According to the orbital parameters of the system the BeppoSAX observation covers the time of an X-ray eclipse should one occur. However, the 1.6-10 keV light curve does…

HydrogenVariable starschemistry.chemical_elementFOS: Physical sciencesAstrophysicsCompact starAstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICAAccretion rateRadio astronomyQuasarsQuàsarsEstels binaris de raigs XOrbital elementsPhysicsSpectral indexRX J1826.2−1450Astrophysics (astro-ph)X-rayIndividual Star ; LS 5039 ; RX J1826.2−1450 ; 3EG J1824−1514 – X-rays ; Variable stars ;; General–radio continuumAstronomy and AstrophysicsIndividual StarLight curveGeneral–radio continuum:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia [UNESCO]StarsEstelsX-ray binarieschemistrySpace and Planetary ScienceRadioastronomiaLS 50393EG J1824−1514 – X-raysUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogoniaOrder of magnitude:ASTRONOMÍA Y ASTROFÍSICA [UNESCO]
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Gaia-ESO Survey: H{alpha} emission stars catalogue

2015

We discuss the properties of H{alpha} emission stars across the sample of 22035 spectra from the Gaia-ESO Survey internal data release, observed with the GIRAFFE instrument and largely belonging to stars in young open clusters. Automated fits using two independent Gaussian profiles and a third component accounting for the nebular emission allow us to discern distinct morphological types of H{alpha} line profiles with the introduction of a simplified classification scheme. Altogether we find 3765 stars with intrinsic emission and sort their spectra into eight distinct morphological categories: single component emission, emission blend, sharp emission peaks, double emission, P-Cygni, inverted…

observational astronomyAstrophysics and AstronomyStellar AstronomyAstrophysics::High Energy Astrophysical PhenomenaPhysicsAstrophysics::Solar and Stellar AstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsPeculiar variable starsNatural SciencesEmission line starsAstrophysics::Galaxy AstrophysicsSpectroscopy
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Equivalent widths for 6 RS CVn systems

2003

Photospheric parameters and abundances are presented for a sample of single-lined chromospherically active binaries from a differential LTE analysis of high-resolution spectra. Abundances have been derived for 13 chemical species, including several key elements such as Li, Mg, and Ca. Cone search capability for table J/A+A/412/495/stars (Stars studied)

observational astronomyAstrophysics and AstronomyStellar AstronomyVariable starsPhysicsNatural SciencesLine intensities
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