On the Relationship of UC H II Regions and Class II Methanol Masers: I. Source Catalogs

TL;DR

This study used VLA observations to catalog and analyze the positions, luminosities, and associations of Galactic Class II methanol masers and ultra-compact H II regions, providing new data on their spatial distribution and properties.

Contribution

First comprehensive catalogs of methanol masers and associated H II regions with precise positions and properties, enabling better understanding of their relationship in the Galaxy.

Findings

No significant correlation between maser luminosities and radio continuum luminosities.

Detected 367 methanol masers out of 372 targeted sources.

Approximately 140 radio continuum sources are physically associated with masers.

Abstract

We conducted VLA C-configuration observations to measure positions and luminosities of Galactic Class II 6.7 GHz methanol masers and their associated ultra-compact H II regions. The spectral resolution was 3.90625 kHz and the continuum sensitivity reached 45 \uJypb. We mapped 372 methanol masers with peak flux densities of more than 2 Jy selected from the literature, 367 of them were detected. Absolute positions have nominal uncertainties of 0.3 arcsec. In this first paper on the data analysis, we present three catalogs, the first gives information on the strongest feature of 367 methanol maser sources, and the second on all detected maser spots. The third catalog present derived data of the 279 radio continuum sources found in the vicinity of maser sources. Among them, 140 show evidence of physical association with maser sources. Our catalogs list properties including distance, flux density, radial velocity and the distribution of masers on the Galactic plane is then provided as well. We found no significant relationship between luminosities of masers and their associated radio continuum counterparts.