J/A+A/341/L79ivo://CDS.VizieR/J/A+A/341/L79doi:10.26093/cds/vizier.33419079CDSTerranegra L.Morale F.Spagna A.Massone G.Lattanzi M.G.2014-02-17T12:34:39Z1999-01-24T16:31:44ZCDS support team

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

cds-question@unistra.frproper-motionslate-type-starsradio-sourcesWe present proper motions of 59 stars of the ROSAT All-Sky Survey (RASS) located in direction of the Chamaeleon star forming region (SFR) in the magnitude range B=5.1-17mag. Proper motions of the fainter stars were newly derived utilizing survey Schmidt plates from the GSC~II plate archive and from a set of special plates taken with the ESO Schmidt telescope. The vector point diagram (VPD) indicates that the certified weak emission-line T Tauri (WTT) stars cluster away from the region occupied by the brighter pre-main-sequence stars (PMS) in Cha I. The distance to this new association is estimated at ~100pc, sensibly smaller than the 150pc generally assumed for the SFR. This yields an upper limit of 2km/s for the velocity dispersion of this new kinematic group. The de-reddened CM diagram of the group members suggest the WTT stars are still PMS objects, but older (3-30Myr) and less massive than previous determinations. These revised age estimates, the newly derived group peculiar velocity, and current distance estimates to the Cha~I/II/III complex would favour in-situ formation against that predicted by high velocity cloud models. Finally, based on a redetermination of the peculiar motions of stars and gas, we speculate that the whole SFR originated from the local Orion spur as a result of more classical mechanisms like interactions with the spiral arms.1999A&A...341..L79Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/341/L79CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/239 : The Hipparcos and Tycho Catalogues (ESA 1997)I/246 : The ACT Reference Catalog (Urban+ 1997)I/146 : Positions and Proper Motions - North (Roeser+, 1988)I/193 : Positions and Proper Motions - South (Bastian+ 1993)J/A+AS/114/109 : Cha X-ray sources + optical identifications (Alcala+ 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/341/L79https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/341/L79http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/341/L79https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/341/L79https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/341/L79http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/341/L79GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapROSATRadiodefaultJ/A+A/341/L79/table1Proper motions for the 59 RASS starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameROSAT all-sky survey source designation Alcala' et al. (1995, Cat. <J/A+AS/114/109>) or catalogue designationmeta.id;meta.maincharn_Name[* KG] Note on Name (1)meta.notecharCatNoAstrometric catalog designationmeta.id;phys.atmol.configuration;meta.tablecharCat[APHS] Catalogue name (2)meta.id;meta.tablecharpmRAProper motion in right ascension ({mu}RA*cosDE)mas/yrpos.pm;pos.eq.rafloate_pmRA? rms uncertainty on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatnullablepmDEProper motion in declinationmas/yrpos.pm;pos.eq.decfloate_pmDE? rms uncertainty on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatnullableplx? Parallax from Hipparcos catalogue (<I/239>)maspos.parallaxfloatnullablee_plx? rms uncertainty on plxmasstat.error;pos.parallaxfloatnullableSpTypeSpectral Typesrc.spTypecharVmag? Stellar V magnitudemagphot.mag;em.opt.VfloatnullableTypeStellar type (3)meta.notecharNamesOther namesmeta.idchar