J/A+A/619/A106ivo://CDS.VizieR/J/A+A/619/A106doi:10.26093/cds/vizier.36190106CDSGrossschedl J.E.Alves J.Meingast S.Ackerl C.Ascenso J.Bouy H.,Burkert A.Forbrich J.Fuernkranz V.Goodman A.Hacar A.,Herbst-Kiss G.Lada C.J.Larreina I.Leschinski K.Lombardi M.,Moitinho A.Mortimer D.Zari E.2020-02-21T08:56:29Z2018-11-15T12:35:43ZCDS support team

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

cds-question@unistra.frvisible-astronomytrigonometric-parallaxyoung-stellar-objectsstellar-distancepre-main-sequence-starsinterstellar-mediumWe use the Gaia DR2 distances of about 700 mid-infrared selected young stellar objects in the benchmark giant molecular cloud Orion A to infer its 3D shape and orientation. We find that Orion A is not the fairly straight filamentary cloud that we see in (2D) projection, but instead a cometary-like cloud oriented toward the Galactic plane, with two distinct components: a denser and enhanced star-forming (bent) Head, and a lower density and star-formation quieter ~75pc long Tail. The true extent of Orion A is not the projected ~40pc but ~90pc, making it by far the largest molecular cloud in the local neighborhood. Its aspect ratio (~30:1) and high column-density fraction (~45%) make it similar to large-scale Milky Way filaments ("bones"), despite its distance to the galactic mid-plane being an order of magnitude larger than typically found for these structures.2018A&A...619A.106Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/619/A106CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/619/A106https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/619/A106http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/619/A106https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/619/A106https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/619/A106http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/619/A106GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/619/A106/tableb1 (YSO sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/619/A106/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/619/A106/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/619/A106/tableb1?GETtext/xml+votable180.050000true82.3473526961993-4.5156646277122610.0055555555555555565/5350 5359 5701 6/21406 21425 21427-21428 21430-21431 21433 21435 21482 22848 22850https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/619/A106?format=asciiOpticaldefaultJ/A+A/619/A106/tableb1YSO samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceThe Gaia DR2 source id (1)meta.id;meta.mainRAICRSRight ascension (ICRS at Ep=2015.5)degpos.eq.ra;meta.mainDEICRSDeclination (ICRS at Ep=2015.5)degpos.eq.dec;meta.mainPlxThe Gaia DR2 parallax (1)maspos.parallaxdoublee_PlxThe Gaia DR2 parallax error (1)masstat.error;pos.parallaxdoubleClass[II F] YSO class taken from Grossschedl et al., 2018, A&A, accepted (VISION III) (2)meta.codecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexed