J/A+A/681/A10ivo://CDS.VizieR/J/A+A/681/A10doi:10.26093/cds/vizier.36810010CDSLiu W.Yan J.Xiao G.Li X.Gao B.Liu Q.2024-11-28T20:05:50Z2024-05-02T09:21:13ZCDS support team

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

cds-question@unistra.frx-ray-binary-starsinfrared-photometryvisible-astronomybroad-band-photometryline-intensities1A 0535+262 is a high-mass X-ray binary that went into a giant X-ray outburst in 2020. During this event, the X-ray luminosity reached the highest value measured over the last 30 years. Our aim is to study the long-term variability of 1A 0535+262 before and after the 2020 major X-ray outburst and to uncover the mechanism that led to the X-ray outburst. We used the long-term photometric light curve and the equivalent widths of the H{alpha} and HeI {lambda}6678 lines to monitor the state of the Be star's circumstellar disk. The H{alpha} line profiles show evidence for V/R variability, which we revealed by fitting the H{alpha} spectral line profiles with two Gaussian functions. In addition, we divided our data into four periods according to the intensity of the X-ray, optical, and infrared emission. The H{alpha} line profiles show single-peaked profiles in most cases. This is consistent with the previously reported orbital inclination of i=37{deg}+/-2{deg}. Unlike the H{alpha} lines, the HeI {lambda}6678 lines show a maximal intensity in October 2020, which is one month before the giant X-ray outburst in 2020. Based on the behavior of the equivalent widths of the H{alpha} and HeI {lambda}6678 lines, and the V-band magnitude, we find two mass ejection processes from the Be star to the Be disk on MJD 55820 and MJD 56600. The V/R quasi-period is about two years during 2011-2015, which is different from 1994 to 1995. Furthermore, the periods I -> II -> III -> IV in the (B-V) color index versus V-band magnitude diagram constitute a cycle. From the behavior of the V/R ratio of H{alpha} lines, and the variability of the V band, we believe that the precession of the density perturbation inside the disk is retrograde.2024A&A...681A..10Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/681/A10CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/PAZh/26/13 : Observations of X-ray binary A0535+26/V725 Tau (Lyuty+, 2000)J/PAZh/31/116 : X-ray binary A0535+26/V725 Tau UBV photometry (Zaitseva, 2005)J/ApJ/660/1398 : Spectro. monitoring of HDE 245770 & X Per (Grundstrom+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/681/A10https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/681/A10http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/681/A10https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/681/A10https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/681/A10http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/681/A10GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.367228618189496e-19 4.920466254354166e-19X-rayOpticalInfrareddefaultJ/A+A/681/A10/tablea1Summary of spectroscopic observations of 1A 0535+262recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableMJDModified Julian datedtime.epochdoubleTelTelescopemeta.id;instr.telcharInstInstrumentmeta.id;instrcharblambdaLower value of wavelength interval0.1nmem.wlintBlambdaUpper value of wavelength interval0.1nmem.wlintEWHaH{alpha} equivalent width0.1nmspect.line.eqWidthfloate_EWHaH{alpha} equivalent width error0.1nmstat.errorfloatEWHIHeI {lambda}6678 equivalent width0.1nmspect.line.eqWidthfloate_EWHIHeI {lambda}6678 equivalent width error0.1nmstat.errorfloatJ/A+A/681/A10/tablea2V/R ratio and peak separation of 1A 0535+262recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableMJDModified Julian datedtime.epochdoubleTelTelescopemeta.id;instr.telcharInstInstrumentmeta.id;instrcharblambdaLower value of wavelength interval0.1nmem.wlintBlambdaUpper value of wavelength interval0.1nmem.wlintlogV/RHaV/R variability of H{alpha} line (1)stat.fit.paramfloatDV(Ha)Peak separation of the violet and red peakskm/sspect.line.widthintJ/A+A/681/A10/tableb1Summary of photometric observations of 1A 0535+26TelTelescopemeta.id;instr.telcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian datedtime.epochdoubleBmag? Johnson B magnitudemagphot.mag;em.opt.Bfloatnullablee_Bmag? Johnson B magnitude errormagstat.error;phot.magfloatnullableVmag? Johnson V magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag? Johnson V magnitude errormagstat.error;phot.magfloatnullableRmag? Cousins R magnitudemagphot.mag;em.opt.Rfloatnullablee_Rmag? Cousins R magnitude errormagstat.error;phot.magfloatnullableImag? Cousins I magnitudemagphot.mag;em.opt.Ifloatnullablee_Imag? Cousins I magnitude errormagstat.error;phot.magfloatnullable