II/180ivo://CDS.VizieR/II/180CDSSchuster W.J.Nissen P.E.2013-02-26T11:31:57Z1997-12-09T16:09:42ZCDS support team

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

cds-question@unistra.frhigh-velocity-starschemically-peculiar-starsUsing the calibrations derived by Schuster and Nissen (=1989A&A...221...65S), the interstellar color excesses, E(b-y), and the metallicities, [Fe/H], have been determined for the 711 high velocity and metal-poor stars in the catalogue of uvby-beta photometry (=1988A&AS...73..225S). 220 of these listed in table1 turn out to be halo stars according to the criterion [Fe/H] <= -1.0. About 15% of the halo stars have colors that are significantly affected by interstellar reddening, i.e. E(b-y) > 0.025. The distributions in the c0-(b-y)0 diagram of the halo stars grouped according to [Fe/H], have well defined turn-off points. From the Teff values of these points a minimum age of 18-20 Gyr for the halo stars is determined. However, this age may be 2-3 Gyr too high due to a possible systematic error in Teff for the stellar models used. Relative ages of 77 halo stars in the turn-off region of the c0-(b-y)0 diagram are derived using the isochrones VandenBerg and Bell (=1985ApJS...58..561V). Assuming that the O/Fe abundance ratio is constant in halo stars, evidence of a cosmic age scatter of +/-2.5Gyr at a given metallicity is found. Furthermore, the mean age of the halo stars is found to decrease smoothly by about 3 Gyr from [Fe/H]= -2.0 to -1.0. These results suggest that a pressure-supported slow uniform collapse controlled the formation and early evolution of the Galaxy. However, the scenario of Searle and Zinn (=1978ApJ...225..357S) is also compatible with the results.1989A&A...222...69Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/II/180CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/97/951 : Metal-poor stars uvby-beta photometry. VI. (Schuster+, 1993)J/A+AS/117/317 : Metal-poor stars uvby-beta photometry. VIII. (Schuster+, 1996)J/A+A/422/527 : Metal-poor stars uvby-beta photometry. X. (Schuster+, 2004)J/A+A/445/939 : Metal-poor stars uvby-beta photometry. XI. (Schuster+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=II/180https://vizier.iucaa.in/viz-bin/VizieR-2?-source=II/180http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=II/180https://vizier.cds.unistra.fr/viz-bin/votable?-source=II/180https://vizier.iucaa.in/viz-bin/votable?-source=II/180http://vizieridia.saao.ac.za/viz-bin/votable?-source=II/180GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table II/180/table1 (The Catalogue)https://vizier.cds.unistra.fr/viz-bin/conesearch/II/180/table1?https://vizier.iucaa.in/viz-bin/conesearch/II/180/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/II/180/table1?GETtext/xml+votable180.050000true2.785697-20.7218120.0055555555555555566/118 146 154 232 375 382 488 650 798 874 1285 1556 1642 2133 2141 2307 3494 3712 4184 4240 4376 4901 4905 5099 5111 5195 5413 5622 5827 6047 6058 6159 6186 6226 6256 6348 6792 6793 7117 7186 7286 7334 8221 8235 8274 9004 9248 9831 9992 10359 12332 12451 12621 12704 13020 13028 13342 13628 13829 14298 14385 14576 14697 15624 16589 16729 16802 16880 17136 17245 17417 17509 17578 17782 18198 18377 18826 18839 18887 19064 19083 19097 19206 19347 19784 19903 20646 21608 21835 21926 22205 22408 22420 23011 23070 23366 23607 23705 23734 23818 23893 23978 24752 25051 25554 25835 25891 25948 26025 26030 26187 26284 26289 26451 27128 27330 27394 27857 27915 27920 27948 27991 28038 28154 28336 28459 28664 28696 29451 29490 29593 29596 30179 30189 30296 30359 30553 30577 30939 31094 31116 31470 31748 31772 31887 32034 32051 32335 32343 32593 32889 33018 33054 33131 33154 33508 33725 33831 34088 34096 34240 34593 34927 35714 35760 36135 36474 36729 36745 36888 36919 38072 38216 38255 39446 39482 39647 39692 40567 40750 40944 41460 42031 42331 43575 43786 44073 44121 44214 44281 44294 44461 44542 44653 44775 44779 44816 44880 45353 46023 46053 46302 46370 46506 46828 47347 47353 47512 47530 47674 48281 48394 48731 48736 48937 49063https://cdsarc.cds.unistra.fr/viz-bin/moc/II/180?format=asciiOpticaldefaultII/180/table1The CataloguerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar designation (HD/DM/Giclas)meta.id;meta.maincharRA1950Right Ascension 1950pos.eq.ra;meta.mainDE1950Declination 1950pos.eq.dec;meta.mainE(b-y)? Interstellar reddeningmagphot.color.excessfloatnullablel_[Fe/H]'<' if [Fe/H] metallicity is an upper limitmeta.code.error;phys.abund.Fechar[Fe/H][-3.5/-1[ Metallicity (relative to Sun)Sunphys.abund.FefloatAge? Age in Giga-yearsGatime.agefloatnullablee_Age? rms error on AgeGastat.error;time.agefloatnullableNotesRemarks (1)meta.notechar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexed