J/AJ/116/1801ivo://CDS.VizieR/J/AJ/116/1801doi:10.26093/cds/vizier.51161801CDSDelgado A.J.Alfaro E.J.Moitinho A.Franco J.2023-04-06T16:50:30Z2007-01-20T08:58:15ZCDS support team

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

cds-question@unistra.fropen-star-clusterspre-main-sequence-starsvisible-astronomyWide-band photometryThe results of a UBV CCD photometric study of the cluster IC 4996 are presented. We obtain new values for the cluster parameters: E(B-V)=0.71+/-0.08, V_0_-M_V_=11.9+/-0.1, and age=(7.5+/-3)x10^6^yr. The combined evidence from the photometric diagrams suggests the presence of a number of premain-sequence (PMS) cluster members with spectral types ~A0 to F5. The interpretation of these objects as PMS candidates is further supported by independent results from CCD uvbyH{beta} observations. If confirmed, these stars would bridge the existing gap in the sample of PMS stars, between the coolest Herbig AeBe stars (HAeBe), and the hottest T Tauri stars. These PMS candidates are located some 0.5 and 1 mag above the main sequence in the V-(B-V) diagram, around the location of spectral types AF. This feature, together with their locations in the (U-B)-(B-V) diagram and the interpretation that they are PMS members, suggest an additional reddening law with a slope {alpha}=E(U-B)/E(B-V)~0.55, probably caused by circumstellar material.1998AJ....116.1801Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/116/1801CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-tohttp://obswww.unige.ch/webda/ : BDA databasehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/116/1801https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/116/1801http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/116/1801https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/116/1801https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/116/1801http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/116/1801GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/116/1801/table2 (Photometry of Hoag et al. (1961PUSNO..17..343H, H61) stars and member stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/1801/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/1801/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/1801/table2?GETtext/xml+votable180.050000true304.1307711137.642039170.0055555555555555566/14641 14643https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/116/1801?format=asciiOpticaldefaultJ/AJ/116/1801/table2Photometry of Hoag et al. (1961PUSNO..17..343H, H61) stars and member starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.id;meta.mainintn_Seq[p*] Note on stars (1)meta.notecharBDA? BDA number (Mermilliod, 1995, http://obswww.unige.ch/webda/meta.idintnullableXposX position (2)pixpos.cartesian.x;instr.detfloatYposY position (2)pixpos.cartesian.y;instr.detfloatVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V colour indexmagphot.color;em.opt.B;em.opt.VfloatU-B? U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullable_RAPosition computed from a comparison with UCAC2 catalog I/289 ({sigma}=0.1'') (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from a comparison with UCAC2 catalog I/289 ({sigma}=0.1'') (declination part)degpos.eq.dec;meta.main