Matching the frequency spectrum of PMS stars by means of standard and rotating models

TL;DR

This study uses detailed standard and rotating PMS models to match observed frequency spectra of young stars, confirming previous findings for one star and providing new insights for another.

Contribution

It introduces a method combining non--rotating and rotating models to analyze PMS star oscillations, improving seismic interpretation accuracy.

Findings

Confirmed mode identification for Star 85 using rotating models.

Provided a new fit for Star 278's frequencies within its error box.

Disputed the hypothesis that Star 278 is much cooler than the red boundary of the instability strip.

Abstract

We applied the ATON code to the computation of detailed grids of standard (non--rotating) and rotating Pre--Main Sequence (PMS) models and computed their adiabatic oscillation spectra,with the aim of exploring the seismic properties of young stars. We adopt a method similar to the matching mode method by Guenther and Brown making use, when necessary, also of our rotating evolutionary code to compute the models for PMS stars. The method is described by a preliminary application to the frequency spectrum of two PMS stars (85 and 278) in the young open cluster NGC 6530. For the Star 85 we confirm, with self--consistent rotating models, previous interpretation of the data, attributing three close frequencies to the mode n=4, l=1 and m=0,+1,--1. For the Star 278 we find a different fit for the frequencies, corresponding to a model within the original error box of the star, and dispute the possibility thatthis star has an effective temperature much cooler that the red boundary of the radial instability strip.