Confirmation of the star J004229.87+410551.8 in M31 as a B[e] supergiant

TL;DR

This study confirms that the star J004229.87+410551.8 in M31 is a B[e] supergiant based on spectroscopic and photometric analysis, including emission lines and infrared excess, clarifying its classification among luminous blue variable candidates.

Contribution

The paper provides the first definitive classification of J004229.87+410551.8 as a B[e] supergiant through detailed spectroscopic and photometric observations.

Findings

Star exhibits FeII, [FeII], [OI], and Balmer emission lines.

Spectral energy distribution shows near-infrared excess due to hot dust.

Star's luminosity estimated at log(L/L_sun)=4.6±0.2.

Abstract

We study the luminous blue variable candidate J004229.87+410551.8 in the Andromeda Galaxy. Earlier, the star displayed a spectral anomaly: although a hot emission spectrum had been detected, it had strong CaII H and K absorption lines. Subsequently the star was assumed to be a hot hypergiant or a B[e] supergiant. For the purpose of clear star classification, we conducted spectroscopic and photometric analysis of the object and its surroundings with the 6-m telescope of SAO RAS, the 3.5-m ARC telescope of the Apache Point Observatory and the 2.5-m telescope of the Caucasus Mountain Observatory of the Sternberg Astronomical Institute. The spectrum of the star has the FeII, [FeII], [OI], and Balmer emission lines. Its spectral energy distribution shows an excess in the near-infrared range due to hot circumstellar dust. The indicated features and a high estimated value of star's luminosity ($\log (L/L_{\odot}) = 4.6\pm 0.2$) allow us to finally classify the object as a B[e] supergiant.