J/MNRAS/493/267ivo://CDS.VizieR/J/MNRAS/493/267doi:10.26093/cds/vizier.74930267CDSSinha T.Sharma S.Pandey A.K.Yadav R.K.Ogura K.Matsunaga N.,Kobayashi N.Bisht P.S.Pandey R.Ghosh A.2024-08-20T20:16:21Z2023-06-21T14:30:02ZCDS support team

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

cds-question@unistra.frvariable-starsyoung-stellar-objectspre-main-sequence-starsproper-motionsvisible-astronomytrigonometric-parallaxstellar-massesstellar-agesphotometryinfrared-astronomyWe present multi-epoch deep (~20mag) Ic-band photometric monitoring of the Sh 2-170 star-forming region to understand the variability properties of pre-main-sequence (PMS) stars. We report identification of 47 periodic and 24 non-periodic variable stars with periods and amplitudes ranging from ~4h to 18d and from ~0.1 to 2.0mag, respectively. We have further classified 49 variables as PMS stars (17 Class II and 32 Class III) and 17 as main-sequence (MS)/field star variables. A larger fraction of MS/field variables (88 per cent) show periodic variability as compared to the PMS variables (59 per cent). The ages and masses of the PMS variable stars are found to be comparable with those of T-Tauri stars. Their variability amplitudes show an increasing trend with the near-IR/mid-IR excess. The period distribution of the PMS variables shows two peaks, one near ~1.5d and the other near ~4.5d. It is found that the younger stars with thicker discs and envelopes seem to rotate slower than their older counterparts. These properties of the PMS variables support the disc-locking mechanism. Both the period and amplitude of PMS stars show decrease with increasing mass probably due to the effective dispersal of circumstellar discs in massive stars. Our results favour the notion that cool spots on weak line T-Tauri stars are responsible for most of their variations, while hot spots on classical T-Tauri stars resulting from variable mass accretion from an inner disc contribute to their larger amplitudes and irregular behaviours.2020MNRAS.493..267Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/493/267CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)II/311 : WISE All-Sky Data Release (Cutri+ 2012)I/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/493/267https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/493/267http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/493/267https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/493/267https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/493/267http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/493/267GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/493/267/table2 (stars identified as members of the Stock 18 cluster)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/493/267/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/493/267/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/493/267/table2?GETtext/xml+votable180.050000true0.39408564.623123060.005555555555555556Cone search capability for table J/MNRAS/493/267/table3 (identified variables and their physical parameters as derived from CMD and/or SED)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/493/267/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/493/267/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/493/267/table3?GETtext/xml+votable180.050000true0.3438561164.6379850.005555555555555556Cone search capability for table J/MNRAS/493/267/table4 (identified YSOs and their physical parameters as derived from their CMD and/or SED)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/493/267/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/493/267/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/493/267/table4?GETtext/xml+votable180.050000true0.3865688964.641273060.0055555555555555566/3067 30701.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/493/267?format=asciiOpticalInfrareddefaultJ/MNRAS/493/267/table1Log of observationsDateObservation datetime.epoch;obsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTelTelescope used for the observationinstr.setupcharFramesNumber of frames observedmeta.numberintExpTimeExposure timestime.duration;obs.exposureintFilterFilter used (V or Ic)instr.setup;instr.filtercharJ/MNRAS/493/267/table2stars identified as members of the Stock 18 clusterSimbadSimbad column added by the CDSmeta.ref.urlcharIDStar internal identifier (MNN)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmag? V-band magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag? Error on Vmagmagstat.error;phot.magfloatnullableIcmag? I_c_-band magnitudemagphot.mag;em.opt.Ifloatnullablee_Icmag? Error on Icmagmagstat.error;phot.magfloatnullableref[ab] References for Vmag and Icmag (1)meta.refcharpmRAProper motion in right ascensionmas/yrpos.pm;pos.eq.rafloate_pmRAError on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in declinationmas/yrpos.pm;pos.eq.decfloate_pmDEError on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatplxParallaxmaspos.parallax.trigfloate_plxError on plxmasstat.error;pos.parallaxfloatProbMembership probability%stat.probabilityintGmagGaia DR2 G-band magnitudemagphot.mag;em.optfloatBP-RP? Gaia DR2 BP-RP colourmagphot.color;em.opt.B;em.opt.RfloatnullableJ/MNRAS/493/267/table3identified variables and their physical parameters as derived from CMD and/or SEDSimbadSimbad column added by the CDSmeta.ref.urlcharNdp? Number of data pointsmeta.numberintnullablee_AgeSED? Error on AgeSEDMyrstat.errorfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameVariable name (VNN)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmag? V-band magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag? Error on Vmagmagstat.error;phot.magfloatnullableIcmag? I_c_-band magnitudemagphot.mag;em.opt.Ifloatnullablee_Icmag? Error on Icmagmagstat.error;phot.magfloatnullableref[abc] References for Vmag and Icmag (G1)meta.refcharPeriod? Variability perioddsrc.varfloatnullablee_Period? Error on Perioddstat.error;time.periodfloatnullableAmpAmplitude of variationmagsrc.var.amplitudefloate_Amp? Error on Ampmagstat.errorfloatnullableRMSRMS dispersion of the magnitudesmagstat.stdevfloatD(Ic-Ks)? NIR colour index {Delta}(I_c_-K_s_) (1)magphot.color;em.IR;em.IRfloatnullablee_D(Ic-Ks)? Error on D(Ic-Ks)magstat.errorfloatnullable3.6-4.5? 3.6-4.5 MIR colour indexmagphot.color;em.IR;em.IRfloatnullablee_3.6-4.5? Error on 3.6-4.5magstat.errorfloatnullableAgeCMD? Age derived from colour-magnitude diagramMyrtime.agefloatnullablee_AgeCMD? Error on AgeCMDMyrstat.errorfloatnullableMassCMD? Mass derived from colour-magnitude diagramsolMassphys.massfloatnullablee_MassCMD? Error on MassCMDsolMassstat.errorfloatnullablechi2SED? Chi-squared for the SED fittingstat.fit.chi2floatnullableAgeSED? Age derived from SED fittingMyrtime.agefloatnullableMassSED? Mass derived from SED fittingsolMassphys.massfloatnullablee_MassSED? Error on MassSEDsolMassstat.errorfloatnullableMdisc? Disc mass from SED fittingsolMassphys.massdoublenullablee_Mdisc? Error on MdiscsolMassstat.errordoublenullableAccrate? Disc accretion rate from SED fittingsolMass/yrarith.ratedoublenullablee_Accrate? Error on AccratesolMass/yrstat.errordoublenullableJ/MNRAS/493/267/table4identified YSOs and their physical parameters as derived from their CMD and/or SEDSimbadSimbad column added by the CDSmeta.ref.urlcharchi2SED? Chi-squared for the SED fittingstat.fit.chi2floatnullableAgeSED? Age derived from SED fittingMyrtime.agefloatnullablee_AgeSED? Error on AgeSEDMyrstat.errorfloatnullableMassSED? Mass derived from SED fittingsolMassphys.massfloatnullablee_MassSED? Error on MassSEDsolMassstat.errorfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameYSO identifier (YNN)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmag? V-band magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag? Error on Vmagmagstat.error;phot.magfloatnullableIcmag? I_c_-band magnitudemagphot.mag;em.opt.Ifloatnullablee_Icmag? Error on Icmagmagstat.error;phot.magfloatnullableAgeCMD? Age derived from colour-magnitude diagramMyrtime.agefloatnullablee_AgeCMD? Error on AgeCMDMyrstat.errorfloatnullableMassCMD? Mass derived from colour-magnitude diagramsolMassphys.massfloatnullablee_MassCMD? Error on MassCMDsolMassstat.errorfloatnullableref[abc] References for Vmag and Icmag (G1)meta.refcharNdp? Number of data pointsmeta.numberintnullableMdisc? Disc mass from SED fittingsolMassphys.massdoublenullablee_Mdisc? Error on MdiscsolMassstat.errordoublenullableAccrate? Disc accretion rate from SED fittingsolMass/yrarith.ratedoublenullablee_Accrate? Error on AccratesolMass/yrstat.errordoublenullableJ/MNRAS/493/267/table5Classification and properties of 71 identified variablesNameVariable name (VNN)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTypeStar classification (1)src.classcharnClassComment on classificationmeta.notecharnVarComment on variabilitymeta.notechar