Oral comunication
R. Costa, T. L. Campante, M. J. P. F. G. Monteiro, N. A. M. Moedas
Abstract
Asteroseismology is the study of oscillations in stars, periodic perturbations
that propagate trough a star, offering one of the best ways to directly probe a star’s inner
structure and improve measurement of global properties of a star such as its mass, age and
radius. The number of stars in which oscillations were detected has increased rapidly in recent
years [1], although these detections have been limited to particular types of stars, mainly main-
sequence stars at least as hot and massive as the Sun as well as red-giant stars [2]. Our work
goes beyond this frontier by being centered on ε Indi, the coldest star in which asteroseismic
oscillations have been detected [3]. Besides aiming to study this newly available observational
data, we will also investigate the issues with current stellar models focusing on the surface term,
a systematic error between the frequencies of oscillation in models and observations, caused by
improper modelling of the stellar atmosphere and convection [4]. Methods: We use advanced
stellar modelling software to model the evolution of stars with properties close to ε Indi [5] along
with their asteroseismic oscillations [6]. Then we use model optimization procedures [7] to
discover the best fitting model and from there derive properties of ε Indi and limitations of the
models. Results: We have created a grid of about 2000 stellar models, in which we vary the mass,
fraction of metals and strength of convection in the model. Through data visualization and
analysis, we have studied how the asteroseismic properties, the inner structure and global stellar
attributes of the models are correlated with the parameters of the grid. Conclusions: We have
confirmed that our grid accurately models the expected properties of cool-dwarf stars, and that
ε Indi is within the range of stars encompassed by it. In the future we will use them for obtaining
more precise values for the mass and age of ε Indi, along with determining the surface term and
its ideal correction method.
IJUP 2024
Porto, Portugal
2024 May
