Analysis of radial fundamental-to-first overtone period ratios in the presence of near degeneracy

TL;DR

This paper investigates how near degeneracy and rotation influence radial mode period ratios in pulsating stars, revealing significant effects that impact stellar parameter determinations and offering insights for improved mode identification.

Contribution

It introduces the analysis of near degeneracy effects on radial mode period ratios, highlighting their impact on Petersen diagrams and stellar parameter estimation.

Findings

Near degeneracy causes significant wriggles in Petersen diagrams.

Wriggles are mainly due to avoided-crossing phenomena.

Effects increase with stellar rotational velocity.

Abstract

In the present work we provide the preliminary results obtained when analysing the rotational Petersen diagrams when including the effects of near degeneracy. We found that near degeneracy affects significantly the fundamental-to-first overtone period ratios, showing wriggles in the Petersen diagrams. Analysis of such wriggles reveals that they are mainly caused by the avoided-crossing phenomenon. The size of wriggles seems to increase with the rotational velocity and could, in certain cases, invalidate any accurate mass and/or metallicity determinations. Nevertheless, deep analysis of near degeneracy effects may allow us to obtain additional information on the mode identification of the radial modes and their corresponding coupled pairs, which would allow us to constrain the modelling.