# HD 46487 is Now a Classical Be Star

## TL;DR

This paper reports the first detection of hydrogen emission around HD 46487, indicating it has recently developed Be star characteristics with a circumstellar disk, despite being a well-studied, dust-free B-type star.

## Contribution

First observation of hydrogen emission in HD 46487 indicating recent Be star activity, highlighting a new phase in its circumstellar environment.

## Key findings

- Hydrogen emission detected only in Hα line
- Absence of infrared dust emission
- Recent onset of Be star features

## Abstract

We present the first observations of hydrogen line emission detected around the B-type star HD 46487, a well-studied star in the CoRoT field of view. The emission is only evident in the H$\alpha$ line, for which the observed violet-red peak separation ($\Delta v_{p}$) is typical of a B$e$ star with a circumstellar disk. The absence of dust emission from the infrared spectral energy distribution excludes the possibility of a very young star. The star's magnitude (V=5.079) and regular use in the literature for a variety of studies suggests that the line emission had a high probability of being found previously, had it been evident; since such was not the case, we believe that the B$e$ phenomenon for HD 46487 has only very recently "turned on." We therefore recommend that this star be spectroscopically and photometrically monitored to track continued changes to its circumstellar morphology.