VizieR Online Data Catalog: Hypercompact H II regions in the Galactic Plane (Yang+, 2019)

Our starting point was the CORNISH (Coordinated Radio 'N' Infrared Survey for High-mass star formation), which we used to form a base 5GHz radio source catalogue. CORNISH was a sensitive (~0.4mJy/beam) and high-resolution (~1.5") 5GHz survey of a section of the Galactic Plane (10<l<65° and |b|<1°), using the JVLA in B and BnA configuration. CORNISH detected 3062 continuum sources greater than 7σ (Hoare et al. 2012PASP..124..939H; Purcell et al. 2013ApJS..205....1P, Cat. J/ApJS/205/1). The Multi-Array Galactic Plane Imaging Survey (MAGPIS) has the highest sensitivity and resolution of the 1.4GHz surveys that we have used, with a resolution of ~6" and noise level ~0.3mJy/beam (Helfand et al. 2006AJ....131.2525H, Cat. J/AJ/131/2525). A catalogue has been published for the survey region 5<l<32° and |b|<0.8°. We used image cutouts available from the MAPGIS Website to identify 1.4GHz counterparts to CORNISH sources in the uncatalogued region of the Galactic Plane. To cover the remainder of the CORNISH survey region, we have used 1-2GHz catalogues and data from The HI, OH, Recombination line survey of the Milky Way (THOR, Bihr et al. 2016A&A...588A..97B, Cat. J/A+A/588/A97; Beuther et al. 2016A&A...595A..32B) and the 1.4GHz VLA survey White et al. (2005AJ....130..586W, Cat. J/AJ/130/586), hereafter White2005.

Once the 1.4-5GHz radio spectral index of the objects has been derived, we select those objects with a positive spectral index and confirm that they are embedded within molecular cloud clumps by examining cutout images from the ATLASGAL (Schuller et al. 2009A&A...504..415S) and Hi-GAL (Molinari et al. 2016A&A...591A.149M, Cat. J/A+A/591/A149) surveys. We found a total of 120 HII regions with positive radio spectral indices, shown in Table A1 and we obtained a sample of 534 objects with a 1.4 to 5GHz spectral index greater than zero, listed in Table A2.

(2 data files).