J/A+A/575/L6ivo://CDS.VizieR/J/A+A/575/L6doi:10.26093/cds/vizier.35759006CDSParedes-Fortuny X.Ribo M.Bosch-Ramon V.Casares J.Fors O.Nunez J.2017-06-19T07:57:55Z2015-02-20T08:26:06ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frx-ray-binary-starsbe-starsccd-photometryline-intensitiesThe gamma-ray binary LS I +61 303 is composed of a Be star and a compact companion orbiting in an eccentric orbit. Variable flux modulated with the orbital period of ~26.5d has been detected from radio to very high-energy gamma-rays. In addition, the system presents a superorbital variability of the phase and amplitude of the radio outbursts with a period of ~4.6yr. We present optical photometric observations of LS I +61 303 spanning ~1.5yr (table 1) and contemporaneous H-alpha equivalent width (EW) data (table 2). The optical photometry shows, for the first time, that the known orbital modulation suffers a positive orbital phase shift and an increase in flux for data obtained 1-yr apart. The orbital modulation of the EW presents, for the first time, a positive orbital phase shift. These orbital phase shifts of the thermal indicators are in line with the observed behavior for nonthermal indicators, such as X-ray or radio emission. This shows that there is a strong coupling between the thermal and nonthermal emission processes in the gamma-ray binary LS I +61 303.2015A&A...575L...6Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/575/L6CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/656/437 : LSI +61 303 radial velocities and Halpha EW (Grundstrom+, 2007)J/ApJ/698/514 : Radial velocities of LSI+61 303 and LS 5039 (Aragona+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/575/L6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/575/L6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/575/L6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/575/L6https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/575/L6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/575/L6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/575/L6/table1Differential optical photometry of LS I +61 303recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Daydtime.epochdoublemagDifferential magnitudemagphot.mag;arith.difffloate_magrms uncertainty on magmagstat.error;phot.magfloatJ/A+A/575/L6/table2H-{alpha} equivalent width of LS I +61 303recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Daydtime.epoch;pos.heliocentricdoubleEWH-{alpha} equivalent width0.1nmspect.line.eqWidthfloate_EWrms uncertainty on EW0.1nmstat.error;spect.line.eqWidthfloat