J/A+A/711/A85ivo://CDS.VizieR/J/A+A/711/A85CDSSoler J.D.Beuther H.Glover S.C.O.Klessen R.S.Ott J.Rugel M.,Teh J.W.Clark S.E.Goldsmith P.Hacar A.Socci A.Heyer M.Lee M.-Y.,Murray C.E.Seifried D.Walch S.Godard B.Miville-Deschenes M.-A.2026-10-10T20:03:50Z2026-07-08T07:42:20ZCDS support team

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

cds-question@unistra.frmolecular-cloudsh-i-line-emissionradio-astronomyThe Orion nebula is the nearest site of ongoing and recent high-mass star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an expanding shell that matches the EON contours delineated by recent observations of ionized carbon ([CII]) line emission. However, our combination of single-dish and interferometric HI observations suggests 100 solar masses of material for the front hemisphere of the shell, which is lower by roughly a factor of ten than the mass inferred from [CII] observations. This discrepancy suggests that the mass of the nearest wind-blown bubble has been overestimated, although we do not rule out the possibility that a significant amount of molecular hydrogen (H_2_) in the shell may account for part of the difference. Our extended 21cm line maps also reveal uncharted structures in and around the EON. They include a probable secondary bubble and a linear protrusion extending roughly four parsecs from the shell boundary. Our results illustrate the potential of HI interferometric observations to elucidate key aspects of the multiphase structure of star-forming regions and their connection to their surroundings.2026A&A...711A..85Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/711/A85CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/711/A85https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/711/A85http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/711/A85https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/711/A85https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/711/A85http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/711/A85GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/711/A85/list (Information of fits data cube)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A85/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A85/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A85/list?GETtext/xml+votable180.050000true83.810022-5.64837140.0055555555555555566/21438https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/711/A85?format=asciiRadiodefaultJ/A+A/711/A85/listInformation of fits data cuberecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintG[G]meta.codecharGLONGalactic longitude of center (J2000)degpos.galactic.lonGLATGalactic latitude of center (J2000)degpos.galactic.latNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNzNumber of pixels along Z-axismeta.numberintbVRADLower value of VRAD intervalm/sphys.veloc;pos.heliocentricintBVRADUpper value of VRAD intervalm/sphys.veloc;pos.heliocentricintdVRADVRAD resolutionm/sspect.resolutionintsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitschar_RA.icrsRight ascension (ICRS) (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.raindexed_DE.icrsDeclination (ICRS) (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.decindexedTitleTitle of the FITS file (1)meta.title;meta.fitschar