Looking for pulsations in HgMn stars through CoRoT lightcurves

TL;DR

This study investigates whether HgMn chemically peculiar stars exhibit pulsations by analyzing high-quality CoRoT satellite lightcurves, finding low amplitude periodic variations in two of three candidate stars consistent with theoretical predictions.

Contribution

First detection of potential pulsations in HgMn stars using space-based photometry, supporting theoretical models of atomic diffusion effects.

Findings

Two stars show low amplitude periodic variations.

Variations have periods of 4.3 and 2.53 days.

Results align with theoretical pulsation predictions.

Abstract

HgMn Chemically Peculiar stars are among the quietest stars of the main-sequence. However, according to theoretical predictions, these stars could have pulsations related to the very strong overabundances of iron peak elements, which are produced by atomic diffusion in upper layers. Such pulsations have never been detected from ground based observations. Our aim is to search for signatures of pulsations in HgMn stars using the high quality lightcurves provided by the CoRoT satellite. We identified three faint stars (V>12), from VLT-GIRAFFE multiobject spectrograph survey in a field which was planned for observation by CoRoT. They present the typical characteristics of HgMn stars. They were observed by the CoRoT satellite during the long run (131 days) which started from the 24th of October 2007, with the exoplanets CCD's (Additional Programme). In the present work, we present the analysis of the ground based spectra of these three stars and the analysis of the corresponding CoRoT lightcurves. Two of these three HgMn candidates show low amplitude (less than 1.6 mmag) periodic variations (4.3 and 2.53 days respectively, with harmonics) which are compatible with periods predicted by theoretical models.