Study of pulsational instabilities in models of $\delta\,$Scuti pulsators discovered under the Nainital-Cape Survey

TL;DR

This study analyzes pulsational instabilities in newly discovered $ ext{delta}$ Scuti stars from the Nainital-Cape Survey using non-adiabatic models, explaining observed variabilities through unstable low order p-modes.

Contribution

It provides the first non-adiabatic stability analysis of these stars, linking observed pulsations to specific unstable low order p-modes.

Findings

Observed pulsation periods match unstable low order p-modes in models.

Several stars' variabilities are explained by radial p-mode pulsations.

Theoretical models support the observed period ranges.

Abstract

Under the Nainital-Cape Survey, eight $\delta\,$Scuti type pulsators have been discovered with the pulsation periods in the range of several minutes to few hours. In order to understand these observed pulsational variabilities, we have performed non-adiabatic linear stability analyses in models of these stars having mass in the range of 1 to 3 M$_{\odot}$. Several low order p-modes are found to be unstable where the pulsation periods associated with these unstable modes are in good agreement with the observed periods. Particularly for HD$\,$118660, HD$\,$113878, HD$\,$102480, HD$\,$98851, and HD$\,$25515, we demonstrate that the observed variabilities can be explained with the low order radial p-mode pulsations.