J/MNRAS/397/1748ivo://CDS.VizieR/J/MNRAS/397/1748doi:10.26093/cds/vizier.73971748CDSBelokurov V.Walker M.G.Evans N.W.Gilmore G.Irwin M.J.Mateo M.,Mayer L.Olszewski E.Bechtold J.Pickering T.2024-07-09T20:15:27Z2010-01-10T21:11:15ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomysloan-photometryradial-velocityWe announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope (MMT). From this, we derive a luminosity of Mv=-2.5, a half-light radius of 34pc and a systemic velocity of ~-40km/s. Our data also provide evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighbouring fields. We resolve the velocity dispersion of Segue 2 as 3.4km/s and the possible stream as ~7km/s. This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites - survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts z>10 and are good candidates for fossils of the reionization epoch.2009MNRAS.397.1748Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/397/1748CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/694/L144 : Spectroscopic study of Leo V (Walker+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/397/1748https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/397/1748http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/397/1748https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/397/1748https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/397/1748http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/397/1748GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/397/1748/table2 (Hectochelle spectroscopy of Segue 2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/397/1748/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/397/1748/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/397/1748/table2?GETtext/xml+votable180.050000true34.81520.15805560.0055555555555555566/618-619 704-705https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/397/1748?format=asciiOpticaldefaultJ/MNRAS/397/1748/table2Hectochelle spectroscopy of Segue 2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqNumber in galaxymeta.id;meta.mainintRAJ2000Rihgt ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainRAngular radius from Segue 2 centerarcminphys.angSizefloatgmagg magnitudemagphot.mag;em.opt.Bfloatimagi magnitudemagphot.mag;em.opt.IfloatHVHeliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HVrms uncertainty on HVkm/sstat.errorfloatsigMg? Composite magnesium index (1)0.1nmspect.indexfloatnullablee_sigMg? rms uncertainty on sigMg0.1nmstat.errorfloatnullableMm[BSY?N] Membership status (2)meta.code.memberchar