BD+14$^\circ$3061: A Luminous Yellow Post-AGB Star in the Galactic Halo

TL;DR

This paper reports the discovery of BD+14°3061 as a luminous, metal-poor yellow post-AGB star in the Galactic halo, highlighting its potential as a Population II standard candle and its binary nature.

Contribution

It identifies BD+14°3061 as a rare yellow post-AGB star in the Galactic halo with detailed properties, expanding understanding of such stars and their use as standard candles.

Findings

BD+14°3061 is a luminous, metal-poor yellow post-AGB star.

It is a high-velocity star on a retrograde orbit.

It is likely a spectroscopic binary with a 429.6-day period.

Abstract

I report the discovery that the 9th-magnitude Galactic-halo star BD+14$^\circ$3061 is a member of the rare class of luminous metal-poor "yellow post-AGB" stars. Its Gaia DR2 parallax implies an absolute magnitude of $M_V=-3.44\pm0.27$, and it is a very high-velocity star moving in a retrograde Galactic orbit. BD+14$^\circ$3061 is a field analog of the half-dozen yellow PAGB stars known in Galactic globular clusters, which have closely similar absolute magnitudes. These objects are the visually brightest members of old stellar populations; their apparently narrow luminosity function makes them potentially useful as Population II standard candles. The spectral-energy distribution of BD+14$^\circ$3061 out to $22\,\mu$m shows no evidence for circumstellar dust. The star is a low-amplitude semi-regular pulsating variable, with typical periods of 30-32 days. A radial-velocity study suggests that it is a spectroscopic binary with a period of 429.6 days, making it similar to known binary yellow PAGB stars such as HD 46703 and BD+39$^\circ$4926.