Wide Field CO Mapping in the Region of IRAS 19312+1950

TL;DR

This study conducted wide field CO mapping around IRAS 19312+1950, revealing a large, chemically-rich molecular component and suggesting the central source is likely a red supergiant based on gas mass and luminosity.

Contribution

First comprehensive CO mapping of IRAS 19312+1950's surrounding region, providing insights into its structure, mass, and nature of the central object.

Findings

Molecular gas mass estimated between 225 and 478 solar masses.

Central source likely a red supergiant based on luminosity and gas mass.

Mapped a 20' x 20' region using multiple CO lines.

Abstract

We report the results of a wide field CO mapping in the region of IRAS 19312+1950. This IRAS object exhibits SiO/H$_2$O/OH maser emission, and is embedded in a chemically-rich molecular component, of which the origin is still unknown. In order to reveal the entire structure and gas mass of the surrounding molecular component for the first time, we have mapped a wide region around IRAS 19312+1950 in the $^{12}$CO $J=1-0$, $^{13}$CO $J=1-0$ and C$^{18}$O $J=1-0$ lines using the Nobeyama 45m telescope. In conjunction with the archival CO maps, we investigated a region with a size up to $20' \times 20'$ around this IRAS object. We calculated CO gas mass assuming the LTE condition, a stellar velocity against to the interstellar medium assuming an analytic model of a bow shock, and absolute luminosity using the latest archival data and trigonometric parallax distance. The derived gas-mass (225 M$_{\odot}$ $-$ 478 M$_{\odot}$) of the molecular component and the relatively large luminosity ($2.63\times10^{4}$ L$_{\odot}$) suggest that the central SiO/H$_2$O/OH maser source seems to be a red supergiant (RSG) rather than an asymptotic giant branch (AGB) star or post-AGB star.