J/MNRAS/301/640ivo://CDS.VizieR/J/MNRAS/301/640doi:10.26093/cds/vizier.73010640CDSWalsh A.J.Burton M.G.Hyland A.R.Robinson G.2024-06-25T20:18:18Z2000-02-21T21:47:44ZCDS support team

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

cds-question@unistra.frh-ii-regionsastrophysical-masersradio-astronomyradial-velocityHigh spatial resolution radio continuum and 6.67-GHz methanol spectral line data are presented for methanol masers previously detected by Walsh et al. (1997, Cat. <J/MNRAS/291/261>). Methanol maser and/or radio continuum emission is found in 364 cases towards IRAS-selected regions. For those sources with methanol maser emission, relative positions have been obtained to an accuracy of typically 0.05arcsec, with absolute positions accurate to around 1arcsec. Maps of selected sources are provided. The intensity of the maser emission does not seem to depend on the presence of a continuum source. The coincidence of water and methanol maser positions in some regions suggests there is overlap in the requirements for methanol and water maser emission to be observable. However, there is a striking difference between the general proximity of methanol and water masers to both cometary and irregularly shaped ultracompact (UC) HII regions, indicating that, in other cases, there must be differing environments conductive to stimulating their emission. We show that the methanol maser is most likely present before an observable UC HII region is formed around a massive star and is quickly destroyed as the UC HII region evolves. There are 36 out of 97 maser sites that are linearly extended. The hypothesis that the maser emission is found in a circumstellar disc is not inconsistent with these 36 maser sites, but is unlikely. It cannot, however, account for all other maser sites. An alternative model which uses shocks to create the masing spots can more readily reproduce the maser spot distributions.1998MNRAS.301..640Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/301/640CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/336/339 : VLA observations of ultracompact HII regions (Molinari+ 1998)J/A+AS/133/29 : Molecular line survey towards UC HII (Hatchell+ 1998)J/MNRAS/291/261 : Methanol maser of IRAS-selected sources (Walsh+ 1997)J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/301/640https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/301/640http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/301/640https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/301/640https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/301/640http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/301/640GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/301/640/table2 (List of the UC HII regions detected)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/301/640/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/301/640/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/301/640/table2?GETtext/xml+votable180.050000true6/21456 21458 21510 22855 28808-28809 28824 28829-28831 28890 28896 28912 28918-28919 29070 29090-29091 29094 29096-29097 29100-29101 29115 29118 29505 29508 29510-29511 29529 29533 29535 30219 30241 30245 30256 30259 30262-30263 30268-30269 37839 37846 37850 37884 37886 37897 37900 37923 38024 39384 39895 41653 41655 41675 41677 41681 41683-41685 41777 41780 41799 41804 41814 41820 42159 42172 42207 42214-42215 42224-42226 42228 42376 42381-42382 42387 42390-42391 42393 42396-42398 42417 42436 42438 42441 42444-42445 42447 42449 42451 42455-42456 42460 42498 43013 43018 43021 43024https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/301/640?format=asciiOpticalRadiodefaultJ/MNRAS/301/640/table2List of the UC HII regions detectedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.intIRASName of IRAS source, used for the pointing centrecharObsDate of Observation (either Aug/94 or Jan/95)charRAJ2000? 8.64GHz radio continuum right ascension (J2000)nullableDEJ2000? 8.64GHz radio continuum declination (J2000)nullablen_RAh[nc] Note (1) (2)charl_S8.64GHz[~] Limit flag on S8.64GHzcharS8.64GHz? 8.64GHz radio continuum integrated flux densitymJyfloatnullableRA1? 6.67GHz methanol maser right ascension (J2000)nullableDE1? 6.67GHz methanol maser declination (J2000)nullablen_RA1h[nc] Note (1) (3)charS6.67GHzm? 6.67GHz methanol maser peak flux density (in Janskys per beam)JyfloatnullableRV? Radial velocity of the methanol maser component, with respect to the local standard of rest (LSR)km/sfloatnullableRA2? 6.67GHz radio continuum right ascension (J2000)nullableDE2? 6.67GHz radio continuum declination (J2000)nullablen_RA2h[nc] Note (2) (1)charS6.67GHzr? 6.67GHz radio continuum integrated flux densitymJyfloatnullable