J/AJ/162/149ivo://CDS.VizieR/J/AJ/162/149doi:10.26093/cds/vizier.51620149CDSHintz E.G.Harding T.B.Hintz M.L.2022-03-21T12:19:54Z2021-12-29T08:55:58ZCDS support team

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

cds-question@unistra.frvariable-starsvisible-astronomyspectroscopyradial-velocityUsing an extensive archive for visual observations from the AAVSO, along with published times of maximum light, we determined a new model for the period of X Cygni. The best model is two linear fits for data before and after 1917 (JD2421512). Before that time the period is 16.38438{+/-}0.00036days. After we find a period of 16.386470{+/-}0.000028days. An examination of the O-C values for data after 1917 shows no clear evidence of a constant period change or of sinusoidal variations. The period looks to be constant. From an examination of H-alpha index measurements we find a drop in the value between data before 2013 October and data after 2014 July. This drop is not related to temperature and is likely related to mass loss in the star. Finally, we find that radial-velocity measurements match well with previously published values and show no seasonal variation over the 11yr of data. This again seems to limit the possibility of a companion.2021AJ....162..149Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/162/149CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/AJ/144/92 : Times of maximum light for the SX Phe star XX Cyg (Yang+, 2012)J/AJ/150/204 : Spectroscopy of standard stars (Joner+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/162/149https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/162/149http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/162/149https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/162/149https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/162/149http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/162/149GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/162/149/table1H{alpha}, H{beta}, and radial velocity values for X CygnirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2455366/2459129] Heliocentric Julian Daydtime.epoch;pos.heliocentricdoubleHalpha[2.62/2.73] H{alpha} indexmagspect.indexfloatHbeta[2.6/2.69]? H{beta} indexmagspect.indexfloatnullableRVel[-22.3/31.6] Radial velocitykm/sphys.veloc;pos.heliocentricfloatJ/AJ/162/149/table2*Times of Maximum Light for X CygnirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2410255/2442373] Heliocentric Julian Daydtime.epoch;pos.heliocentricdoubleCycle[-2049/-89] Cycle number of maximumtime.phaseintTypeType of Observationsmeta.code;obscharOC[-0.65/2.21] Observed minus Calculated Time Maximumdstat.fit.residualfloatJ/AJ/162/149/table3New times of maximum light for X CygnirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2443011/2459168] Heliocentric Julian Daydtime.epoch;pos.heliocentricdoubleCycle[-50/936] Cycle number of maximumtime.phaseintTypeType of Observationsmeta.code;obscharOC[-1.28/0.89] Observed minus Calculated Time of Maximumdstat.fit.residualfloatRefSource of Time of Maximum light (1)meta.bibcharJ/AJ/162/149/fig4Continuum calibrated spectra of X CygnirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[4496/6939] Wavelength; Angstroms0.1nmem.wldoubleI[0.29/1.25] Relative Intensityspect.line.intensity;arith.ratiofloatJ/AJ/162/149/fig6O-C diagram around time of H{alpha} shiftrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2445731/2459123] Heliocentric Julian Daydtime.epoch;pos.heliocentricdoubleOC[-0.41/0.41] Observed-Calculateddstat.fit.residualfloat