Short timescale variables in stellar clusters: From Gaia to ground-based telescopes

TL;DR

This paper explores Gaia's potential to detect short timescale stellar variability in clusters, assesses detection capabilities through simulations, and develops ground-based follow-up methods to enhance understanding of stellar physics.

Contribution

It evaluates Gaia's short timescale variability detection capabilities and introduces a pipeline for ground-based high-cadence photometry follow-up.

Findings

Gaia can detect variability with amplitudes above a few millimagnitudes.

Simulations show Gaia's effectiveness in identifying short timescale variables.

Ground-based telescopes can complement Gaia with high-cadence observations.

Abstract

Combined studies of variable stars and stellar clusters open great horizons, and they allow us to improve our understanding of stellar cluster formation and stellar evolution. In that prospect, the Gaia mission will provide astrometric, photometric, and spectroscopic data for about one billion stars of the Milky Way. This will represent a major census of stellar clusters, and it will drastically increase the number of known variable stars. In particular, the peculiar Gaia scanning law offers the opportunity to investigate the rather unexplored domain of short timescale variability (from tens of seconds to a dozen of hours), bringing invaluable clues to the fields of stellar physics and stellar aggregates. We assess the Gaia capabilities in terms of short timescale variability detection, using extensive light-curve simulations for various variable object types. We show that Gaia can detect periodic variability phenomena with amplitude variations larger than a few millimagnitudes. Additionally, we plan to perform subsequent follow-up of variables stars detected in clusters by Gaia to better characterize them. Hence, we develop a pipeline for the analysis of high cadence photometry from ground-based telescopes such as the 1.2m Euler telescope (La Silla, Chile) and the 1.2m Mercator telescope (La Palma, Canary Islands).