Considerations on the Origin of IRAS 19312+1950 Based on Long-Term Maser Observations

TL;DR

This study investigates IRAS 19312+1950's nature through long-term maser observations, revealing complex features that suggest it may be an evolved star, a Water Fountain, or a Red Nova Remnant, but its exact classification remains uncertain.

Contribution

It provides the first long-term maser monitoring of I19312, highlighting its peculiar properties and discussing possible evolutionary scenarios.

Findings

SiO masers show wide velocity range and variability

OH masers suggest evolved star characteristics

H$_2$O masers indicate molecular outflows

Abstract

IRAS source 19312+1950 (hereafter I19312) is an infrared point source with maser emissions of SiO, H$_2$O, and OH molecules. Although initial observations suggested that I19312 might be an evolved star, its characteristics are not fully consistent with this classification. This study aims to further investigate the nature of I19312 by conducting long-term monitoring of its maser emissions and comparing the results with other known astrophysical objects. We conducted long-term monitoring of SiO, H$_2$O, and OH maser emissions using single-dish radio telescopes. The results were then compared with historical maser data and the characteristics of similar objects to infer the possible origin of I19312. The SiO maser emissions from I19312 were detected over a wide velocity range and exhibited significant time variability. The OH maser lines suggest characteristics of an evolved star, while the H$_2$O maser lines indicate molecular outflows. These features suggest that I19312 could be a candidate for a Water Fountain (WF) star, though there are inconsistencies, such as the large molecular gas mass, that challenge this hypothesis. The possibility of I19312 being a Red Nova Remnant (RNR) is also considered, but this remains speculative due to the lack of direct evidence. The evolutionary stage of I19312 remains unclear, but it shares multiple characteristics with both evolved stars with peculiar properties and RNRs. Further long-term monitoring and high-resolution interferometric observations are required to better constrain the nature of this object.