J/AJ/161/193ivo://CDS.VizieR/J/AJ/161/193doi:10.26093/cds/vizier.51610193CDSLi L.-J.Qian S.-B.Zhu L.-Y.He J.-J.Fang X.-H.2023-12-20T08:24:44Z2021-08-17T07:41:37ZCDS support team

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

cds-question@unistra.frvariable-starsmultiple-starsinfrared-photometryvisible-astronomybroad-band-photometryThe pulsation periods of RR-Lyrae stars usually vary with time, and they are often used as probes to study the mechanism behind the variation. After the early discovery that the pulsation period of the RR-Lyrae star AXUMa decreased rapidly, in further research, we made multiband photometric observations of this star using the Sino-Thai 70cm telescope and the 60cm telescope at Yunnan Observatories, and collected its light-curve data from several photometry sky surveys. The O-C diagram confirmed that AX UMa has a rapid period decrease with a rate of -7.752{+/-}0.005days/Myr, which indicates that it is the fastest-period decreasing ab-type RR Lyrae star in the Galactic field. Moreover, the O-C residuals contain additional periodic variations. We suppose that the variation with a long period is probably caused by the light-travel time effect as the star orbits in a binary system. The calculation shows that the lower mass limit of the companion is about 1M{sun}. Combined with the full amplitudes and color indexes, we suggested that the companion is probably a hot subdwarf star. We compared the light curves of AXUMa and those of another binary evolution pulsator, OGLE-BLG-RRLYR-02792, and found that the former shows the characteristics of ab-type RR-Lyrae stars, while the latter is more like an extreme long-period c-type RR-Lyrae star. However, the absence of a bump in the light curves implies that the mass loss has occurred in the outer atmosphere of AXUMa. The special features of AXUMa make it worth more attention and further observations.2021AJ....161..193Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/161/193CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/MNRAS/368/1757 : Catalogue of RR Lyrae from NSVS (Wils+, 2006)J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)J/AJ/139/2639 : DY Peg times of light maximum (Li+, 2010)J/other/IBVS/5959 : Minima and maxima of 436 variables (Huebscher+, 2011)J/AJ/144/39 : Galactic RRab stars from GEOS RR Lyr Survey (Le Borgne+, 2012)J/A+A/589/A94 : TU UMa light curves and maxima, CL Aur minima (Liska+, 2016)J/ApJ/863/151 : Period analysis of 7 field RRab stars (Li+, 2018)J/AJ/158/93 : Regression of stellar Teff in GaiaDR2 (Bai+, 2019)J/A+A/635/A66 : Humps and bumps in RR Lyrae stars (Prudil+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/161/193https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/161/193http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/161/193https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/161/193https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/161/193http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/161/193GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/AJ/161/193/table1Times of light maximum and corresponding errors of AX UMa determined from photometric surveys and our observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[27291/58512] Times of light maximum, HJD-2400000dtime.epochdoublee_HJD[0.0002/0.01]? Uncertainty in HJDdstat.error;time.epochfloatnullableMethodMethod used (1)meta.code;obscharEpoch[-33808/24550] Epoch (cycle)time.epochintO-C[-6.66/0.08] O-C, Equation 2dstat.fit.residualfloatRefReference or source (2)meta.ref;pos.framecharJ/AJ/161/193/fig9Color curves of AX UMa obtained by Sino-Thai 70cm telescoperecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPhase[-0.25/1.25] Phasetime.phasefloatColor[-0.01/0.63] Color Indexmeta.code;phot.colorfloatRefColor Code; B-V, R-I, V-I or V-Rmeta.ref;pos.framechar