J/ApJ/849/150ivo://CDS.VizieR/J/ApJ/849/150doi:10.26093/cds/vizier.18490150CDSCohen J.G.Sesar B.Bahnolzer S.He K.Kulkarni S.R.Prince T.A.,Bellm E.Laher R.R.2019-12-10T06:59:42Z2018-07-19T13:13:24ZCDS support team

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

cds-question@unistra.frvariable-starsvisible-astronomysloan-photometryradial-velocitystellar-distanceRR Lyrae stars are ideal massless tracers that can be used to study the total mass and dark matter content of the outer halo of the Milky Way (MW). This is because they are easy to find in the light-curve databases of large stellar surveys and their distances can be determined with only knowledge of the light curve. We present here a sample of 112 RR Lyr stars beyond 50kpc in the outer halo of the MW, excluding the Sgr streams, for which we have obtained moderate-resolution spectra with Deimos on the Keck II Telescope. Four of these have distances exceeding 100kpc. These were selected from a much larger set of 447 candidate RR Lyr stars that were data-mined using machine-learning techniques applied to the light curves of variable stars in the Palomar Transient Facility database. The observed radial velocities taken at the phase of the variable corresponding to the time of observation were converted to systemic radial velocities in the Galactic standard of rest. From our sample of 112 RR Lyr stars we determine the radial velocity dispersion in the outer halo of the MW to be ~90km/s at 50kpc, falling to about 65km/s near 100 kpc once a small number of major outliers are removed. With reasonable estimates of the completeness of our sample of 447 candidates and assuming a spherical halo, we find that the stellar density in the outer halo declines as r^-4^.2017ApJ...849..150Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/849/150CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/315 : UCAC3 Catalogue (Zacharias+ 2009)J/MNRAS/375/1381 : Kinematics of RR Lyr and HB stars in NGP (Kinman+, 2007)J/ApJ/678/851 : RR Lyrae survey in the Galactic Halo (Keller+, 2008)J/ApJ/678/865 : LONEOS-I RR Lyrae stars (Miceli+, 2008)J/ApJ/684/1143 : BHB candidates in the Milky Way (Xue+, 2008)J/ApJ/701/1053 : Abundances of 8 stars in the Draco dSph (Cohen+, 2009)J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)J/AJ/139/59 : Milky Way halo velocity dispersion profile (Brown+, 2010)J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)J/AJ/142/187 : HST obs. of 7 Pop.II variable stars (Benedict+, 2011)J/ApJ/740/65 : VLA search for 5GHz radio transients (Ofek+, 2011)J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011)J/ApJ/738/79 : SDSS-DR8 BHB stars in the Milky Way's halo (Xue+, 2011)J/AJ/144/114 : Radial velocities of 6 field RR Lyrae (Sesar+, 2012)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/ApJ/756/23 : V-band follow-up of RR Lyrae from SEKBO (Akhter+, 2012)J/ApJ/763/32 : Galactic halo RRab stars from CSS (Drake+, 2013)J/ApJ/776/26 : RRab stars in the Orphan stream distances (Sesar+, 2013)J/AJ/146/21 : LINEAR. II. Catalog of RR Lyrae stars (Sesar+, 2013)J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)J/ApJ/793/135 : Positions and distances of RR Lyrae stars (Sesar+, 2014)J/ApJ/784/170 : SEGUE K giant survey. II. Dist. of 6036 stars (Xue+, 2014)J/ApJ/788/105 : XSTPS RR Lyrae in the north Galactic cap (Faccioli+, 2014)J/A+A/584/A44 : Photom. classification of QSO from RCS-2 (Carrasco+, 2015)J/MNRAS/446/2251 : Southern Catalina Survey type-ab RR Lyrae (Torrealba+, 2015)J/ApJ/817/73 : QSOs & RR Lyrae in PS1 3{pi} Data (Hernitschek+ 2016)J/ApJ/838/107 : Distances to RRab stars from WISE and Gaia (Sesar+, 2017)J/ApJ/844/L4 : PS1 RRab for tracing outer Virgo overdensity (Sesar+, 2017)J/AJ/153/204 : RR Lyrae stars from the PS1 3{pi} survey (Sesar+, 2017)http://www.ptf.caltech.edu/news/DR3 : The Palomar Transient Facility DR3http://www.sdss3.org/ : The SDSS-III home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/849/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/849/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/849/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/849/150https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/849/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/849/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/849/150/rrlyrcand (Light curve parameters and radial velocities for the RR Lyr candidates (tables 1 and 2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/849/150/rrlyrcand?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/849/150/rrlyrcand?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/849/150/rrlyrcand?GETtext/xml+votable180.050000true3.7763228.376040.0055555555555555566/688 695 750 2135 2148 4386 4718 4782 5416 5507 5700 7409 7417 8230 8566 8907 8987 9191 9280 9403 9410 9463 9487 9523 9610 9655 9756 9773 9802 9856 9857 10242 10343 10362 10374 10399 10460 10485 10521 10539 10541 10543 10596 10599 10640 10678 10705 10755 10812 10820 10844 10869 10873 10976 11074 11284 11381 11806 12305 12355 12573 12608 12621 12626 12632 12635 12636 13344 13347 13430 13586 18190 18383 18666 18723 18921 18989 18990 18999 19054 19178 19232 19280 19283 19298 19354 19388 19431 19490 19762 19765 19799 19974 19983 20056 20077 20321 20352 20430 22366 22993 25590 26090 26339 26353 26363 27441 27763 28522 28543 28614 30038 31538 31692 31722 32450https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/849/150?format=asciiOpticaldefaultJ/ApJ/849/150/rrlyrcandLight curve parameters and radial velocities for the RR Lyr candidates (tables 1 and 2)SimbadNameSimbad column added by the CDSmeta.idcharNsp[1/2] Number of spectrameta.numberintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSgrSgr, a=Probable Sgr Streammeta.codecharPer[0.4/0.9] Perioddtime.perioddoubleHJD[55007.9/57538.7] Epoch of maximum light in heliocentric Julian date; HJD-2400000 (1)dtime.epochdoubleAmpR[0.4/1.2] Amplitude of variation in PTF-R bandmagarith.rate;phot.magfloatRmag[0/20.7]? Mean PTF-R band AB magnitudemagphot.mag;em.opt.RfloatnullableN(R)[0/723]? Number of PTF-R band epochs star detected in late 2016meta.numberintnullableN(g)[0/385]? Number of PTF-g band epochs star detected in late 2016meta.numberintnullableQual[0/3]? Quality (2)meta.code.qualintnullableRAJ2000Right ascension, decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination, decimal degrees (J2000)degpos.eq.dec;meta.mainDist[50/109.1] Heliocentric distancekpcpos.distancefloatRV-GSR[-256.2/224] Radial velocity, Galactic system of rest (3)km/sphys.veloc;pos.galactocentricfloate_RV-GSR[12/29] Uncertainty in RVelkm/sstat.errorfloatDateApproximate RV date of observation MM/YYYY or MM/DD/YYYY; "dup" = 2 spectra takentime.epoch;obscharf_NspFlag on spectra taken (4)meta.codecharS17Display data from the PS1 catalog of RR Lyrae stars (Sesar+, 2017, J/AJ/153/204) within 0.5"meta.ref.urlintnullableSloanDisplay the online SDSS data for the nearest objectmeta.ref.urlchar