J/ApJ/786/97ivo://CDS.VizieR/J/ApJ/786/97doi:10.26093/cds/vizier.17860097CDSHerczeg G.J.Hillenbrand L.A.2017-09-04T08:00:49Z2017-07-04T10:51:44ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsstellar-distancestellar-spectral-typesextinctionstellar-radiistellar-massesstellar-agesEstimates of the mass and age of young stars from their location in the H-R diagram are limited by not only the typical observational uncertainties that apply to field stars, but also by large systematic uncertainties related to circumstellar phenomena. In this paper, we analyze flux-calibrated optical spectra to measure accurate spectral types and extinctions of 281 nearby T Tauri stars (TTSs). The primary advances in this paper are (1) the incorporation of a simplistic accretion continuum in optical spectral type and extinction measurements calculated over the full optical wavelength range and (2) the uniform analysis of a large sample of stars, many of which are well known and can serve as benchmarks. Comparisons between the non-accreting TTS photospheric templates and stellar photosphere models are used to derive conversions from spectral type to temperature. Differences between spectral types can be subtle and difficult to discern, especially when accounting for accretion and extinction. The spectral types measured here are mostly consistent with spectral types measured over the past decade. However, our new spectral types are one to two subclasses later than literature spectral types for the original members of the TW Hya Association (TWA) and are discrepant with literature values for some well-known members of the Taurus Molecular Cloud. Our extinction measurements are consistent with other optical extinction measurements but are typically 1 mag lower than near-IR measurements, likely the result of methodological differences and the presence of near-IR excesses in most CTTSs. As an illustration of the impact of accretion, spectral type, and extinction uncertainties on the H-R diagrams of young clusters, we find that the resulting luminosity spread of stars in the TWA is 15%-30%. The luminosity spread in the TWA and previously measured for binary stars in Taurus suggests that for a majority of stars, protostellar accretion rates are not large enough to significantly alter the subsequent evolution.2014ApJ...786...97Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/786/97CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/297/391 : T Tauri stars ROSAT survey (Neuhaeuser+, 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/786/97https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/786/97http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/786/97https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/786/97https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/786/97http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/786/97GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/786/97/table14 (Stellar Properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/786/97/table14?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/786/97/table14?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/786/97/table14?GETtext/xml+votable180.050000true43.8574520.08099440.0055555555555555565/270 292 5887 6/246 325 336 337 342 377 380 490 597 599 768 770 857 862 1029 1031 1037 1039 1040 1042 1047 1048 1050 1051 1052 1054 1061 1063 1068 1073 1074 1075 1078 1111 1114 1115 1123 1124 1126 1136 1154 1156 1157 1159 1539 22895 23543 24183 24189 24191 24198 24201 24203 24221 24232 24262 24269 24276 24294 24295 24300 24449 24608 24629 24763 25113 30733 38191 38347 38359 38363 38382 38687 38742 38800 39389 42611 42614 42704 42705 42707 42713 42714 42727 42736 42737 42981 42990 43677 43704 44317 44356 44363 44366 44379 44385 44389 44397 47739 47742 47826 47828 47845https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/786/97?format=asciiOpticaldefaultJ/ApJ/786/97/table14Stellar PropertiesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource identifiermeta.id;meta.maincharOName2MASS identifier or other name if no 2MASS identifiermeta.idcharDateDate of the Observationtime.epochnullabledDistancepcpos.distance;pos.heliocentricintSpTypeSpectral typesrc.spTypecharRFlag[rc] Results flag (1)meta.codecharAV? V band extinction (2)magphys.absorption;em.opt.VfloatnullablelogFLog photospheric flux at 7510 {AA} (3)log(cW.m**-2.nm**-1)phot.fluxfloatr7510? Veiling at 7510 {AA} (4)phys.absorptionfloatnullablelogL? Log luminosity (4)log(solLum)phys.luminosityfloatnullableRad? Radius (4)solRadphys.size.radiusfloatnullableMass? Mass (4)solMassphys.massfloatnullablelogA? Log age (5)log(yr)time.agefloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main