J/A+AS/120/283ivo://CDS.VizieR/J/A+AS/120/283CDSHofner P.Churchwell E.2022-09-02T09:07:47Z2022-09-02T10:06:31ZCDS support team

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

cds-question@unistra.frastrophysical-masersradio-astronomyIn this paper we present high resolution images and spectra toward 21 H_2_O maser sources in the vicinity of ultracompact (UC) HII regions. This survey provides the basis for future studies with milli-arcsecond resolution, utilizing very long baseline interferometry (VLBI) techniques. Emission from the 6_16_-5_23_ masing transition of interstellar H_2_O is observed in the close vicinity of UC HII regions with a median angular distance of 2.9" and a median linear projected distance of 0.1pc from the continuum peak. We find that for UC HII regions with cometary morphology the water maser emission is located in front of the cometary arc whereas for non-cometary UC HII regions the water masers are often observed projected onto the contours of the ionized gas. Due to the large median distance of the water masers from the I-front of the UC HII region, it is unlikely, that the water masers are formed in the shocked layer of warm molecular gas in the interface between the ionized gas of the UC HII region and surrounding molecular gas which is predicted by the Bow Shock theory of UC HII regions. A comparison with maps in the NH_3_ inversion transitions shows that in at least 7 cases, the water masers are associated with hot (T>100K), dense (n(H_2_)=~10^7^cm^-3^) molecular clumps. For the UC HII regions G5.89-0.38 and G45.07+0.13 we find spatial and velocity correspondence between water masers and outflowing molecular gas. It is thus likely, that for these sources the H_2_O masers are taking part in the bipolar outflow.1996A&AS..120..283Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+AS/120/283CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/133/29 : Molecular line survey towards UC HII (Hatchell+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+AS/120/283https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+AS/120/283http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+AS/120/283https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+AS/120/283https://vizier.iucaa.in/viz-bin/votable?-source=J/A+AS/120/283http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+AS/120/283GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+AS/120/283/table3 (Observed water maser features)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/120/283/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/120/283/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/120/283/table3?GETtext/xml+votable180.050000true270.12638132-24.064661170.0055555555555555566/14622 28912 28919 29091 29094 29096-29097 29101 29114 29510-29511 30259 30269 30312 30318 30328 30420 30616-30617 30622 30701https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+AS/120/283?format=asciiRadiodefaultJ/A+AS/120/283/table3Observed water maser featuresSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceSource namemeta.id;meta.maincharNoNumber of maser clustermeta.numberintm_NoMultiplicity index on Nometa.code.multipcharRA1950Right ascension (1950)pos.eq.ra;meta.mainDE1950Declination (1950)pos.eq.dec;meta.mainVlsrLSR velocity of featurekm/sphys.veloc;pos.lsrfloatInuIntensity of feature (Jy/beam)Jyphot.flux.density;em.radio.12-30GHzfloatDeltaVVelocity range over which emission is observed in the clusterkm/sphys.veloc;phys.emissMeasurefloatn_DeltaV[ab] Note (1)meta.notechar_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)pos.eq.ranullableindexed_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)pos.eq.decnullableindexed