Matching the Spectral Energy Distribution and p Mode Oscillation Frequencies of the Rapidly Rotating Delta Scuti Star ? Ophiuchi with a 2D Rotating Stellar Model

TL;DR

This study uses a 2D rotating stellar model to match the spectral energy distribution and p mode oscillation frequencies of the rapidly rotating Delta Scuti star ? Ophiuchi, achieving close agreement with observations.

Contribution

It presents a novel 2D rotating stellar model that accurately reproduces both the spectral energy distribution and oscillation frequencies of ? Ophiuchi, improving upon spherical models.

Findings

Model matches ultraviolet and visible spectra of ? Oph.

Oscillation mode frequencies agree within observational errors for most modes.

Including nonaxisymmetric modes increases the match rate to 24 out of 35 modes.

Abstract

Spectral energy distributions are computed using 2D rotating stellar models and NLTE plane parallel model atmospheres. A rotating, 2D stellar model has been found which matches the observed ultraviolet and visible spectrum of ? Oph. The SED match occurs for the interferometrically deduced surface shape and inclination, and is different from the SED produced by spherical models. The p mode oscillation frequencies in which the latitudinal variation is modelled by a linear combination of eight Legendre polynomials were computed for this model. The five highest and seven of the nine highest amplitude modes show agreement between computed axisymmetric, equatorially symmetric mode frequencies and the mode frequencies observed by MOST to within the observational error. Including nonaxisymmetric modes up through |m| = 2 and allowing the possibility that the eight lowest amplitude modes could be produced by modes which are not equatorially symmetric produces matches for 24 out of the 35 MOST modes to within the observational error and another eight modes to within twice the observational error. The remaining three observed modes can be fit within 4.2 times the observational error, but even these may be fit to within the observational error if the criteria for computed modes are expanded.