CoRoT 102749568: mode identification in a delta Scuti star based on regular spacings

TL;DR

This study uses regular frequency spacings and multi-method analysis to identify pulsation modes in the delta Scuti star CoRoT 102749568, achieving detailed mode identification and physical parameter estimation.

Contribution

It introduces a combined approach of frequency regularities, spectroscopy, and multi-colour photometry for mode identification in a non-asymptotic delta Scuti star.

Findings

Identified 9 pulsation modes directly.

Determined the dominant mode as the radial first overtone.

Constrained stellar parameters like log g using large frequency separation.

Abstract

The high accuracy of space data increased the number of the periodicities determined for pulsating variable stars, but the mode identification is still a critical point in the non-asymptotic regime. We use regularities in frequency spacings for identifying the pulsation modes of the recently discovered delta Sct star ID 102749568. In addition to analysing CoRoT light curves (15252 datapoints spanning 131 days), we obtained and analysed both spectroscopic and extended multi-colour photometric data. We applied standard tools (MUFRAN, Period04, SigSpec, and FAMIAS) for time-series analysis. A satisfactory light-curve fit was obtaining by means of 52 independent modes and 15 combination terms. The frequency spacing revealed distinct peaks around large (25.55-31.43 microHz), intermediate (9.80, 7.66 microHz), and low (2.35 microHz) separations. We directly identified 9 modes, and the l and n values of other three modes were extrapolated. The combined application of spectroscopy, multi-colour photometry, and modelling yielded the precise physical parameters and confirmed the observational mode identification. The large separation constrained the log g and related quantities. The dominant mode is the radial first overtone.