J/ApJ/764/172ivo://CDS.VizieR/J/ApJ/764/172doi:10.26093/cds/vizier.17640172CDSPandey A.K.Eswaraiah C.Sharma S.Samal M.R.Chauhan N.Chen W.P.,Jose J.Ojha D.K.Yadav R.K.Chandola H.C.2018-01-05T08:55:55Z2014-11-20T14:50:07ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomybroad-band-photometrypolarimetryopen-star-clustersyoung-stellar-objectsstellar-agesWe present optical photometric and polarimetric observations of stars toward NGC 1931 with the aim of deriving cluster parameters such as distance, reddening, age, and luminosity/mass function as well as understanding dust properties and star formation in the region. The distance to the cluster is found to be 2.3+/-0.3kpc and the reddening E(B-V) in the region is found to be variable. The stellar density contours reveal two clusters in the region. The observations suggest a differing reddening law within the cluster region. Polarization efficiency of the dust grains toward the direction of the cluster is found to be less than that for the general diffuse interstellar medium (ISM). The slope of the mass function (-0.98+/-0.22) in the southern region in the mass range of 0.8<M/M_{sun}_<9.8 is found to be shallower in comparison to that in the northern region (-1.26+/-0.23), which is comparable to the Salpeter value (-1.35). The K-band luminosity function (KLF) of the region is found to be comparable to the average value of the slope (~0.4) for young clusters obtained by Lada & Lada (2003ARA&A..41...57L); however, the slope of the KLF is steeper in the northern region as compared to the southern region. The region is probably ionized by two B2 main-sequence-type stars. The mean age of the young stellar objects (YSOs) is found to be 2+/-1Myr, which suggests that the identified YSOs could be younger than the ionizing sources of the region. The morphology of the region, the distribution and ages of the YSOs, and ionizing sources indicate a triggered star formation in the region.2013ApJ...764..172Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/764/172CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)J/MNRAS/396/964 : T Tauri in and around bright-rimmed clouds (Chauhan+, 2009)J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)J/MNRAS/383/1241 : UBVIc photometry of cluster Berkeley 59 (Pandey+, 2008)J/AJ/132/1669 : Wide-field CCD phot. around 9 open clusters (Sharma+, 2006)J/PAZh/25/10 : Young open clusters space-age distribution (Dambis, 1999)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/764/172https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/764/172http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/764/172https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/764/172https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/764/172http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/764/172GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/764/172/table2 (UBV(RI)c photometric data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/764/172/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/764/172/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/764/172/table2?GETtext/xml+votable180.050000true82.7498083334.2588750.005555555555555556Cone search capability for table J/ApJ/764/172/table6 (Observed polarization, polarization angles, and estimated Serkowski parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/764/172/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/764/172/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/764/172/table6?GETtext/xml+votable180.050000true82.859634.186066110.0055555555555555566/1297 1300 24507 245102.367228618189496e-19 6.118840631666147e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/764/172?format=asciiInfraredOpticaldefaultJ/ApJ/764/172/table2UBV(RI)c photometric dataPolDisplay the polarization measures in table 6 (if any)meta.ref.urlintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/1579] Star running sequence numbermeta.id;meta.mainintprimaryRAJ2000[5] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[34] Degree of Declination (J2000)pos.eq.dec;meta.mainUmag? The U band magnitudemagphot.mag;em.opt.Ufloatnullablee_Umag? The 1{sigma} uncertainty in Umagmagstat.error;phot.mag;em.opt.UfloatnullableBmag? The B band magnitudemagphot.mag;em.opt.Bfloatnullablee_Bmag? The 1{sigma} uncertainty in Bmagmagstat.error;phot.mag;em.opt.BfloatnullableVmag[10.7/21.8] The V band magnitudemagphot.mag;em.opt.Vfloate_Vmag[0.001/0.1] The 1{sigma} uncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatRmag? The R_C_ band magnitudemagphot.mag;em.opt.Rfloatnullablee_Rmag? The 1{sigma} uncertainty in Rmagmagstat.error;phot.mag;em.opt.RfloatnullableImag[9.3/20.4] The I_C_ band magnitudemagphot.mag;em.opt.Ifloate_Imag[0.001/0.9] The 1{sigma} uncertainty in Imagmagstat.error;phot.mag;em.opt.IfloatYSOSimbad column added by the CDSmeta.ref.urlintnullable2MDisplay the 2MASS data within 2" (Cat. II/246) for the YSOsmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/764/172/table6Observed polarization, polarization angles, and estimated Serkowski parameterseps[0.06/14]? <{epsilon}> parameter (5)stat.fit.paramfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_SeqNote on Seq (1)meta.notecharSeq[1/2003] Star identification numbermeta.id;meta.mainintf_Seq[a] Optical data not available (2)meta.codecharRAJ2000[5] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainVpol[0.3/8.7]? Degree of polarization in V-band%phys.polarization;em.opt.Vfloatnullablee_Vpol[0.08/1.1]? Vpol uncertainty%stat.errorfloatnullableVpa[6.1/173]? V-band polarization angledegpos.posAng;phys.polarizationfloatnullablee_Vpa[1.1/11]? Vpa uncertaintydegstat.errorfloatnullableRpol[0.3/6.4]? Rc-band polarization degree%phys.polarization;em.opt.Rfloatnullablee_Rpol[0.08/0.8]? Rpol uncertainty%stat.errorfloatnullableRpa[2.7/180]? Rc-band polarization angledegpos.posAng;phys.polarizationfloatnullablee_Rpa[0.9/9]? Rpa ncertaintydegstat.errorfloatnullableIpol[0.3/6.9]? Ic-band polarization degree%phys.polarization;em.opt.Ifloatnullablee_Ipol[0.05/0.7]? Ipol uncertainty%stat.errorfloatnullableIpa[-3.3/175]? Ic-band polarization angledegpos.posAng;phys.polarizationfloatnullablee_Ipa[0.8/9]? Ipa uncertaintydegstat.errorfloatnullablePmax[0.4/8.3]? Peak polarization occurring at wavelength {lambda}_max_ (3)%phys.polarization;stat.maxfloatnullablee_Pmax[0.06/1]? Pmax uncertainty%stat.errorfloatnullablelam.m[0.3/0.9]? Wavelength {lambda}_max_ (3)umem.wlfloatnullablee_lam.m[0.04/0.3]? lam.m uncertaintyumstat.errorfloatnullablesig1[0.05/3.2]? {sigma}_1_ parameter (4)stat.errorfloatnullableJ/ApJ/764/172/table9*Age and mass of YSOs obtained in the present studyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[32/1575] Star numbermeta.id;meta.mainintl_AgeLimit flag on Agemeta.code.error;time.agecharAge[0.4/5] AgeMyrtime.agefloate_Age[0.1/1.5]? Age uncertaintyMyrstat.error;time.agefloatnullableMass[0.3/3.5] MasssolMassphys.massfloate_Mass[0.1/0.3] Mass uncertaintysolMassstat.error;phys.massfloatPolDisplay the polarization measures in table 6 (if any)meta.ref.urlintnullable