Rotational Splitting of Pulsational Modes

TL;DR

This paper investigates how rotation affects pulsational mode splittings in 2D stellar models, revealing that rotation induces asymmetry and overlaps in mode splittings, which can help infer internal angular momentum distribution.

Contribution

It provides a detailed analysis of mode splitting patterns in differentially rotating stars, highlighting their potential to diagnose internal rotation profiles.

Findings

Mode splitting becomes asymmetric at slow rotation rates.

Large mode splittings overlap with different radial and latitudinal modes.

Differential rotation produces distinct splitting patterns from uniform rotation.

Abstract

Mode splittings produced by uniform rotation and a particular form of differential rotation are computed for two-dimensional rotating 10 Mo ZAMS stellar models. The change in the character of the mode splitting is traced as a function of uniform rotation rate, and it is found that only relatively slow rotation rates are required before the mode splitting becomes asymmetric about the azimuthally symmetric (m=0) mode. Increased rotation produces a progressively altered pattern of the individual modes with respect to each other. Large mode splittings begin to overlap with the mode splittings produced by different radial and latitudinal modes at relatively low rotation rates. The mode splitting pattern for the differentially rotating stars we model is different than that for uniformly rotating stars, making the mode splitting a possible discriminant of the internal angular momentum distribution if one assumes the formidable challenge of mode identification can be overcome.