J/A+A/640/A9ivo://CDS.VizieR/J/A+A/640/A9doi:10.26093/cds/vizier.36400009CDSMartin E.L.Lodieu N.Bejar V.J.S.2020-10-09T09:49:50Z2020-07-31T05:42:08ZCDS support team

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

cds-question@unistra.fropen-star-clustersinfrared-photometryvisible-astronomysloan-photometryWe mainly aim to search for the lithium depletion boundary (LDB) among the sub-stellar population of the open star cluster Coma Berenices. Since the number of brown dwarf candidates in Coma Ber available in the literature is scarce, we carried out a search for additional candidates photometrically using colour-magnitude diagrams combining optical and infrared photometry from the latest public releases of the following large-scale surveys: the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIRT/UKIDSS), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), the Sloan Digital Sky Survey (SDSS), and AllWISE. We checked astrometric consistency with cluster membership using Gaia DR2. A search for Li in three new and five previously known brown dwarf candidate cluster members was performed via spectroscopic observations using the OSIRIS instrument at the 10.4m Gran Telescopio de Canarias (GTC). A couple dozen new photometric candidate brown dwarfs located inside the tidal radius of Coma Ber are reported, but none of these are significantly fainter and cooler than previously known members. No LiI resonance doublet at 6707.8{AA} was detected in any of eight Coma Ber targets in the magnitude range J=15-19 and G=20-23 observed with the GTC. Spectral types and radial velocities were derived from the GTC spectra. These values confirm the cluster membership of four L2-L2.5 dwarfs, two of which are new in the literature. The large Li depletion factors found among the four bona fide sub-stellar members in Coma Ber implies that the LDB must be located at spectral type later than L2.5 in this cluster. Using the latest evolutionary models for brown dwarfs, a lower limit of 550Myr on the cluster age is set. This constraint has been combined with other dating methods to obtain an updated age estimate of 780+/-230Myr for the Coma Ber open cluster. Identification of significantly cooler sub-stellar cluster members in Coma Ber awaits the advent of the Euclid wide survey, which should reach a depth of about J=23; this superb sensitivity will make it possible to determine the precise location of the sub-stellar LDB in this cluster and to carry out a complete census of its sub-stellar population.2020A&A...640A...9Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/640/A9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/640/A9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/640/A9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/640/A9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/640/A9https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/640/A9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/640/A9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/640/A9/table1 (List of Coma Ber photometric member candidates identified in the area common to the three large-scale public surveys considered in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/640/A9/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/640/A9/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/640/A9/table1?GETtext/xml+votable180.050000true182.81208323.5944170.0055555555555555566/28063 28085-28086 28089 28105-28108 28130 28133 28139-28140 28156 28433 28435 28443 28445 28481-28483 28485 28489 28491 28493 28496 28499 28505 28516 285308.305533028865447e-20 6.090060298487514e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/640/A9?format=asciiOpticalInfrareddefaultJ/A+A/640/A9/table1List of Coma Ber photometric member candidates identified in the area common to the three large-scale public surveys considered in this workumag? SDSS DR12 u magnitudemagphot.mag;em.opt.UfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDUKIDSS GCS ID numbermeta.id;meta.mainintRAJ2000Rigth ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainZmagUKIDSS GCG DR9 Z magnitudemagphot.mag;em.opt.IfloatYmagUKIDSS GCG DR9 Y magnitudemagphot.mag;em.IR.JfloatJmagUKIDSS GCG DR9 J magnitudemagphot.mag;em.IR.JfloatHmagUKIDSS GCG DR9 H magnitudemagphot.mag;em.IR.HfloatKmagUKIDSS GCG DR9 K magnitudemagphot.mag;em.IR.KfloatimagPSPan-STARR DR1 i magnitudemagphot.mag;em.opt.IfloatzmagPSPan-STARR DR1 z magnitudemagphot.mag;em.opt.IfloatymagPSPan-STARR DR1 y magnitudemagphot.mag;em.IR.Jfloatgmag? SDSS DR12 g magnitudemagphot.mag;em.opt.Bfloatnullablermag? SDSS DR12 r magnitudemagphot.mag;em.opt.Rfloatnullableimag? SDSS DR12 i magnitudemagphot.mag;em.opt.Ifloatnullablezmag? SDSS DR12 z magnitudemagphot.mag;em.opt.Ifloatnullable