J/ApJ/883/8ivo://CDS.VizieR/J/ApJ/883/8doi:10.26093/cds/vizier.18830008CDSCasetti-Dinescu D.I.Girard T.M.2021-09-10T14:58:50Z2021-03-11T07:52:45ZCDS support team

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

cds-question@unistra.frob-starsultraviolet-photometryvisible-astronomysurveystrigonometric-parallaxproper-motionsWe combine Galaxy Evolution Explorer and Gaia DR2 catalogs to track star formation in the outskirts of our Galaxy. Using photometry, proper motions, and parallaxes we identify a structure of ~300 OB-type candidates located between 12 and 15kpc from the Galactic center that are kinematically cold. The structure is located between l=120{deg} and 200{deg}, above the plane up to ~700pc and below the plane to ~1kpc. The bulk motion is disklike; however, we measure a mean upward vertical motion of 5.7+/-0.4km/s, and a mean outward radial motion of between 8 and 16km/s. The velocity dispersion along the least dispersed of its proper-motion axes (perpendicular to the Galactic disk) is 6.0+/-0.3km/s, confirming the young age of this structure. While spatially encompassing the outer spiral arm of the Galaxy, this structure is not a spiral arm. Its explanation as the Milky Way warp is equally unsatisfactory. The structure's vertical extent, mean kinematics, and asymmetry with respect to the plane indicate that its origin is more akin to a wobble generated by a massive satellite perturbing the Galaxy's disk. The mean stellar ages in this outer structure indicate the event took place some 200Myr ago.2019ApJ...883....8Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/8CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/242 : LEDA galaxies with DENIS measurements catalog (Paturel+, 2005)VI/137 : GaiaSimu Universe Model Snapshot (Robin+, 2012)II/335 : Revised cat. of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/543/A100 : GaiaSimu Universe Model Snapshot (Robin+, 2012)J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)J/MNRAS/441/715 : MIR study of RR Lyrae stars (Gavrilchenko+, 2014)J/ApJ/783/130 : Plx of high mass star forming regions (Reid+, 2014)J/MNRAS/448/2260 : WD candidates in SDSS DR10 (Gentile Fusillo+, 2015)J/ApJS/221/12 : AGNs in the MIR using AllWISE data (Secrest+, 2015)J/ApJS/224/7 : CO obs. of the outer arm in the 2nd quadrant (Du+, 2016)J/ApJS/224/4 : GOSSS III. O-type systems (Maiz Apellaniz+, 2016)J/A+A/614/A140 : Large Quasar Astrometric Catalogue 4 (Gattano+, 2018)J/A+A/618/A93 : Gaia DR2 open clusters in the MW (Cantat-Gaudin+, 2018)J/A+A/616/A10 : Open clusters GaiaDR2 HR diag. (Gaia Collaboration, 2018)J/A+A/616/L15 : Parallaxes and Proper Motions of OB stars (Xu+, 2018)J/A+A/621/A38 : Gaia catalogue of hot subluminous stars (Geier+, 2019)J/A+A/622/A60 : Gaia DR2 misclassified RR Lyrae list (Clementini+, 2019)J/MNRAS/485/2312 : Outer Galactic disk A & F star motions (Harris+, 2019)J/ApJS/241/32 : OB stars from the LAMOST DR5 spectra (Liu+, 2019)J/A+A/642/A21 : Astrometric parameters for 135 OB stars (Russeil+, 2020)J/A+A/645/L8 : Plx & PMs of OB stars from Gaia EDR3 (Xu+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/8https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/8http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/8https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/8https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/8http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/8GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/883/8/table3 (List of OB candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/883/8/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/883/8/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/883/8/table3?GETtext/xml+votable180.050000true88.4167186.6162890.0055555555555555565/313 339 353 369 454 464 832 6/1102 1103 1104 1107 1110 1111 1112 1114 1115 1130 1136 1140 1145 1146 1147 1182 1222 1223 1224 1225 1227 1228 1238 1239 1244 1246 1260 1262 1267 1270 1275 1279 1282 1289 1290 1313 1315 1316 1318 1324 1351 1355 1362 1371 1372 1377 1380 1381 1382 1400 1408 1409 1422 1441 1444 1448 1450 1510 1513 1515 1516 1518 1595 1617 1618 1620 1626 1654 1801 1805 1811 1815 1820 1823 1841 1845 1847 1860 1864 1868 1890 1897 1937 1939 1940 1942 1945 1947 1948 1963 1966 1969 1970 1972 1974 1977 1983 2008 3159 3207 3222 3315 3321 3322 3323 3324 3332 3334 3335 3336 3337 3340 3341 3344 3345 3346 3360 3362 3363 3364 3365 3366 3369 3371 3372 3457 3482 3645 3653 3664 3688 3701 3709 3791 3801 3836 6186 23603 23608 23609 23610 23612 23614 24051 24120 24162 24216 24245 24246 24253 24268 24269 24270 24292 24293 24294 24296 24318 24385 24433 24524 24528https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/883/8?format=asciiUVOpticaldefaultJ/ApJ/883/8/table3List of OB candidatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia DR2 object identifiermeta.id;meta.mainGALEXGALEX object identifiermeta.id.crossGLON[121.7/201] Galactic longitudedegpos.galactic.lonGLAT[-15/14.7] Galactic latitudedegpos.galactic.latPlx[-0.11/0.25] Gaia DR2 Parallaxmaspos.parallaxfloatpmGLON[-2/1.5] Proper motion, Galactic longitudemas/yrpos.pm;pos.galactic.lonfloatpmGLAT[-0.8/0.8] Proper motion, Galactic latitudemas/yrpos.pm;pos.galactic.latfloate_Plx[0.018/0.1] Uncertainty in Plxmasstat.error;pos.parallaxfloate_pmGLON[0.02/0.2] Uncertainty in pmGLONmas/yrstat.errorfloate_pmGLAT[0.02/0.2] Uncertainty in pmGLATmas/yrstat.errorfloatGB0[11.34/15.51] Reddening corrected, Gaia BP magnitudemagphot.mag;em.opt.BfloatGR0[12/15.7] Reddening corrected, Gaia RP magnitudemagphot.mag;em.opt.RfloatFUV0[9.17/16.75] Reddening corrected, GALEX FUV magnitudemagphot.mag;em.UVfloatNUV0[8.94/16.7] Reddening corrected, GALEX NUV magnitudemagphot.mag;em.UVfloate_FUV0[0.007/0.2] Uncertainty in GALEX FUV0magstat.errorfloate_NUV0[0.005/0.1] Uncertainty in GALEX NUV0magstat.errorfloatSep[0.02/2.9] Separationarcsecpos.angDistancefloatE(B-V)[0.06/1.3] Reddening, Schlegel+ (1998ApJ...500..525S)magphot.color.excessfloat_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decnullableindexed