A radio loud semiregular variable

TL;DR

This paper reports the discovery of a semiregular variable star with unusually high radio emission, likely caused by a stellar wind ionized by external photons, expanding understanding of stellar wind phenomena.

Contribution

It identifies a new SRb type semiregular variable star with high radio emission and proposes a novel explanation involving external ionizing radiation affecting stellar wind properties.

Findings

Classified IRC-10412 as a new SRb variable star.

Measured a high mass-loss rate of ~1E-5 Msun/yr.

Suggested external ionizing photons influence the star's radio emission.

Abstract

As a byproduct of our search for Galactic stellar systems with gamma-ray emission, we have identified an unrelated cool and evolved star (IRC-10412) that attracted our attention due to its strong radio emission level with a spectral index matching, almost perfectly, the canonical +0.6 value expected from an ionized stellar wind. A follow-up observational analysis was undertaken given that these two properties are hard to reconcile as originating in the same stellar object. As a result, IRC-10412 has been classified as a new semiregular variable of SRb type in the asymptotic giant branch, and different but consistent estimates of its mass-loss parameter are reported. We propose that its unusually high radio emission arises from a ~ 1E-5 Msun/yr stellar wind exposed to an external source of ionizing photons, possibly coming from nearby OB associations.