The Effects of Metallicity on Convective Overshoot Behaviour in Models of delta Scuti Variable Stars

• Main Authors: Dornan, V, Lovekin, C. C
• Format: Journal Article
• Language: English
• Published: 23-11-2021
• Subjects: Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.2111.12068

delta Scuti variables are stars which exhibit periodic changes in their
luminosity through radial and non-radial pulsations. Internally, these stars
have relatively small convective cores, and convective overshoot can
significantly affect the size. Recently, models of radial pulsation in delta
Scuti stars found a strong correlation between the pulsation constant (Q) as a
function of effective temperature and the amount of convective overshoot within
the star. However, only models with metallicities of Z = 0.02 were examined,
leaving the dependence of this relationship on chemical composition unknown. In
this work, we have extended the models' pulsation properties using GYRE. By
varying the models' mass, rotation speed, convective overshoot, and
metallicity, we studied the behaviour of Q at low temperature. We found that
the updated convective boundary treatment in MESA changes the overshoot
dependence found previously, and the value of the slope depends on both
rotation and overshoot. We also found that there is a metallicity dependence in
the Q values. The lowest metallicity models in our grid reached higher
temperatures than previously studied, revealing a parabolic relation between
log Q and log Teff.