dc.contributor.author | Yang, A. Y. | |
dc.contributor.author | Thompson, M. A. | |
dc.contributor.author | Tian, W. W. | |
dc.contributor.author | Bihr, S. | |
dc.contributor.author | Beuther, H. | |
dc.contributor.author | Hindson, L. | |
dc.date.accessioned | 2019-01-10T14:00:07Z | |
dc.date.available | 2019-01-10T14:00:07Z | |
dc.date.issued | 2019-01-11 | |
dc.identifier.citation | Yang , A Y , Thompson , M A , Tian , W W , Bihr , S , Beuther , H & Hindson , L 2019 , ' A search for hypercompact HII regions in the Galactic Plane ' , Monthly Notices of the Royal Astronomical Society , vol. 482 , no. 2 , pp. 2681–2696 . https://doi.org/10.1093/mnras/sty2811 | |
dc.identifier.issn | 0035-8711 | |
dc.identifier.other | ArXiv: http://arxiv.org/abs/1809.00404v1 | |
dc.identifier.other | ORCID: /0000-0001-5392-909X/work/54917663 | |
dc.identifier.uri | http://hdl.handle.net/2299/20948 | |
dc.description | 22 pages, 8 figures, 6 tables, accepted by MNRAS | |
dc.description.abstract | We have carried out the largest and most unbiased search for hypercompact (HC) H II regions. Our method combines four interferometric radio continuum surveys (THOR, CORNISH, MAGPIS, and White2005) with far-infrared and sub-mm Galactic Plane surveys to identify embedded H II regions with positive spectral indices; 120 positive spectrum H II regions have been identified from a total sample of 534 positive spectral index radio sources. None of these H II regions, including the known HC H II regions recovered in our search, fulfills the canonical definition of an HC H II region at 5 GHz. We suggest that the current canonical definition of HC H II regions is not accurate and should be revised to include a hierarchical structure of ionized gas that results in an extended morphology at 5 GHz. Correlating our search with known ultracompact (UC) H II region surveys, we find that roughly half of detected UC H II regions have positive spectral indices, instead of more commonly assumed flat and optically thin spectra. This implies a mix of optically thin and thick emission and has important implications for previous analyses which have so far assumed optically thin emission for these objects. Positive spectrum H II regions are statistically more luminous and possess higher Lyman continuum fluxes than H II regions with flat or negative indices. Positive spectrum H II regions are thus more likely to be associated with more luminous and massive stars. No differences are found in clump mass, linear diameter, or luminosity-to-mass ratio between positive spectrum and non-positive spectrum H II regions. | en |
dc.format.extent | 16 | |
dc.format.extent | 722477 | |
dc.language.iso | eng | |
dc.relation.ispartof | Monthly Notices of the Royal Astronomical Society | |
dc.subject | Infrared: ISM | |
dc.subject | ISM: H II regions | |
dc.subject | Radio continuum: ISM | |
dc.subject | Submillimetre: ISM | |
dc.subject | Astronomy and Astrophysics | |
dc.subject | Space and Planetary Science | |
dc.title | A search for hypercompact HII regions in the Galactic Plane | en |
dc.contributor.institution | Centre for Astrophysics Research (CAR) | |
dc.contributor.institution | School of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
dc.identifier.url | http://www.scopus.com/inward/record.url?scp=85058482841&partnerID=8YFLogxK | |
dc.identifier.url | https://arxiv.org/abs/1809.00404 | |
rioxxterms.versionofrecord | 10.1093/mnras/sty2811 | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |