Gaia DR 2 data and the evolutionary status of eight high velocity hot post-AGB candidates

TL;DR

This study uses Gaia DR2 data to determine the distances, luminosities, and evolutionary status of eight high velocity hot post-AGB star candidates, revealing their true proximity and initial masses, and identifying two new high velocity post-AGB stars.

Contribution

First Gaia DR2-based analysis of these candidates providing accurate distances, luminosities, and evolutionary classifications, including the discovery of two new high velocity post-AGB stars.

Findings

Six stars have accurate parallaxes enabling precise distance and luminosity calculations.

Most stars are nearby post-AGB stars with initial masses between 1 and 2 solar masses.

LSE 148 is likely a post-horizontal branch or post-early-AGB star.

Abstract

From Gaia DR 2 data of eight high velocity hot post-AGB candidates LS 3593, LSE 148, LS 5107, HD 172324, HD 214539, LS IV -12 111, LS III +52 24, and LS 3099, we found that six of them have accurate parallaxes which made it possible to derive their distances, absolute visual magnitudes (M_V) and luminosity (log L/L_sun). Except LS 5107 all the remaining seven stars have accurate effective temperature (T_eff) in the literature. Some of these stars are metal-poor and some of them do not have circumstellar dust shells. In the past the distances of some stars were estimated to be 6~kpc which we find it to be incorrect. The accurate Gaia DR2 parallaxes show that they are relatively nearby post-AGB stars. When compared with post-AGB evolutionary tracks we find their initial masses in the range of 1M_sun to 2M_sun. We find the luminosity of LSE 148 to be significantly lower than that of post-AGB stars, suggesting that this is a post-horizontal branch star or post-early-AGB star. LS 3593 and LS 5107 are new high velocity hot post-AGB stars from Gaia DR2.