A Radio-loud Semiregular Variable

• Published in: The Astrophysical journal Vol. 973; no. 2; pp. 127 - 136
• Main Authors: Luque-Escamilla, Pedro L., Martí, Josep
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.10.2024; IOP Publishing
• Subjects: Asymptotic giant branch stars; Emissions; Gamma emission; Gamma rays; Parameter estimation; Radio emission; Semiregular variable stars; Stellar mass loss; Stellar systems; Stellar winds; Variable stars
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad6842

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 ∼10 −5 M ⊙ yr −1 stellar wind exposed to an external source of ionizing photons, possibly coming from nearby OB associations.