Predictions of gravity mode pulsations of collisional blue straggler stars in globular clusters

TL;DR

This paper investigates the pulsation properties of collisional blue straggler stars in globular clusters, revealing seismic signatures that can help determine their formation history.

Contribution

It introduces a grid of low-metallicity collisional BSS models and identifies unique seismic patterns linked to their formation processes.

Findings

Collision products show distinctive chemical stratification.

Gravity mode period-spacing patterns are affected by collision history.

Seismic fingerprints can trace BSS formation pathways.

Abstract

Blue straggler stars (BSSs) are exotic objects, which, being the results of processes such as mass transfer, mergers, or collisions, are considered key objects in the study of their host clusters' dynamics. While many studies on astrometric, spectroscopic, and photometric properties of BSSs in clusters have been conducted, there are few works in the literature regarding their pulsations and internal structure, which can indeed retain traces of their origin. In this work we computed and analysed a grid of collisional BSSs at low metallicity ($Z = 0.01\; Z_\odot$), finding that collision products present a peculiar chemical stratification that leads to periodicities in the period-spacing pattern of high-order gravity modes. These seismic fingerprints provide a unique opportunity to constrain the formation pathways of BSSs in globular clusters.