Molecular Line Observations of the SiO Maser Source IRAS 19312+1950

TL;DR

This paper investigates the complex molecular chemistry of IRAS 19312+1950, a unique SiO maser source, through review and preliminary VLBI observations, challenging its classification as an oxygen-rich evolved star.

Contribution

It provides new VLBI observational data and discusses the chemical complexity of IRAS 19312+1950, questioning its evolutionary status.

Findings

Rich molecular chemistry observed in IRAS 19312+1950

Preliminary VLBI results presented for maser lines

Challenges the typical classification of the source

Abstract

IRAS 19312+1950 is a unique SiO maser source, exhibiting a rich set of molecular radio lines, although SiO maser sources are usually identified as oxygen-rich evolved stars, in which chemistry is relatively simple comparing with carbon-rich environments. The rich chemistry of IRAS 19312+1950 has raised a problem in circumstellar chemistry if this object is really an oxygen-rich evolved star, but its evolutional status is still controversial. In this paper, we briefly review the previous observations of IRAS 19312+1950, as well as presenting preliminary results of recent VLBI observations in maser lines.