Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions

TL;DR

This study confirms that 6.7-GHz methanol masers are exclusively associated with high-mass star formation regions, refuting previous suggestions of their link to evolved stars, and clarifies their role in star formation studies.

Contribution

The paper provides definitive evidence that 6.7-GHz methanol masers are only found in high-mass star formation regions, dismissing claims of their association with evolved stars.

Findings

No evidence of methanol masers in evolved star environments

One suspected evolved star maser was a spurious detection

Confirmed exclusive association with high-mass star formation regions

Abstract

Recently, a comparison between the locations of 6.7-GHz methanol masers and dust continuum emission has renewed speculation that these masers can be associated with evolved stars. The implication of such a scenario would be profound, especially for the interpretation of large surveys for 6.7-GHz masers, individual studies where high-mass star formation has been inferred from the presence of 6.7-GHz methanol masers, and for the pumping mechanisms of these masers. We have investigated the two instances where 6.7-GHz methanol masers have been explicitly suggested to be associated with evolved stars, and we find the first to be associated with a standard high-mass star formation region, and the second to be a spurious detection. We also find no evidence to suggest that the methanol maser action can be supported in the environments of evolved stars. We thereby confirm their exclusive association with high-mass star formation regions.