Letter to the Editor

Identifying blue large-amplitude pulsators in the Galactic plane using Gaia DR2: a case study

Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, UK
e-mail: gavin.ramsay@armagh.ac.uk

Received: 8 November 2018
Accepted: 23 November 2018

Abstract

Blue large-amplitude pulsators (BLAPs) are blue stars emitting high-amplitude (> 0.2 mag) pulsations on a timescale of a few tens of minutes. Recently discovered using OGLE data, they form a new class of variable star and have inspired a number of investigations searching for the origin of their pulsations. This short study presents the Gaia DR2 data for ten BLAPs for which parallax measurements are available. We have dereddened their colours using Gaia DR2 data from the stars in their immediate field and find that six show absolute magnitude and intrinsic colour consistent with expectations, whilst four stars have a less certain classification. This work highlights the extra information that Gaia DR2 data can provide to help classify those variable stars for which moderate-resolution optical spectra are not currently available. We also show how Gaia DR2 can make searches for BLAPs in wide-field high-cadence surveys more systematic and robust.