Modelling gravity-mode pulsators in the open cluster NGC 2516
Abstract
Gravity-mode pulsators on the main sequence have demonstrated an extraordinary ability to reveal stellar near-core properties. However, seismic modelling of such targets heavily relies on stellar parameters, such as luminosity and temperature, which may contain unavoidable systematic deviations in the case of single stars. Therefore, we focus on g-mode pulsators in open clusters. Stars within the same open cluster share identical properties in terms of distance, metallicity, extinction, and age. The colour–magnitude diagram provides direct and reliable constraints not only on stellar parameters but also on age. Therefore, we expect that the synergy between asteroseismology and open clusters facilitates our seismic modelling. In this poster, we present our results on the simultaneous modelling of multiple g-mode pulsators in the young open cluster NGC 2516. We find that, even within the same cluster, fitting individual pulsators separately yields different ages. However, demanding that these pulsators share the same age and fitting them together, we obtain an asteroseismic cluster age of 132 ± 8 Myr. This seismic age makes the cluster older than its isochronal age (approximately 102 ± 10 Myr), which may result from differences in the adopted input physics. We also constrain other stellar parameters, and find that the masses derived from isochrones cannot reproduce the asteroseismic signals in some cases, a problem known as the ‘mass discrepancy’ occurring as well in binary research. Moreover, our asteroseismic constraints on internal mixing processes suggest that stars exhibit different levels of mixing, which strongly affects their evolution. Such diversity in internal mixing among cluster members has hardly been studied so far and introduces uncertainties in the stellar and cluster's evolution.