Might intermediate-order g modes observed in the CoRoT hybrid gamma Doradus/delta Scuti star HD 49434 be stochastically excited?

TL;DR

This study investigates whether intermediate-order g modes observed in the hybrid star HD 49434 are stochastically excited, using statistical methods, but results remain inconclusive due to sampling effects.

Contribution

It applies a statistical analysis to determine the excitation mechanism of observed g modes in a hybrid star, highlighting the need for improved sampling considerations.

Findings

Preliminary results are inconclusive regarding stochastic excitation.

Sampling effects significantly impact the analysis.

Further analysis is required for definitive conclusions.

Abstract

The primary target in the seismo-field of CoRoT, HD 49434, known to be a bona fide hybrid gamma Doradus/delta Scuti, shows excited intermediate-order g modes. Time-Dependent Convection models, however, predict a range in frequency that is stable to pulsations, between the simultaneously excited high-order g modes (gamma Dor) and low-order p and g modes (delta Sct). Furthermore, theoretical studies based on model computations of delta Sct stars suggest that stochastically excited modes are likely to be observed. A pertinent question would then be to ask: Might those observed intermediate-order g modes be stochastically excited? By employing a statistical method which searches for the signature of stochastic excitation in stellar pulsations, we investigate the nature of those modes with possible implications on the identification of their excitation mechanism. Preliminary results are rather inconclusive about the presence of stochastic excitation. A new analysis that thoroughly takes into account sampling effects is necessary in order to get more reliable results.