Close-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observations

TL;DR

This study combines ground-based spectroscopic and photometric observations to analyze pulsation frequencies in selected CoRoT targets, revealing multiple modes and hybrid star characteristics, thereby enhancing asteroseismic understanding.

Contribution

It provides the first detailed ground-based pulsation analysis of selected CoRoT targets, identifying multiple frequencies and hybrid star behavior, complementing space-based data.

Findings

HD 50844 shows over ten pulsation frequencies, including a possible radial fundamental mode.

HD180642 exhibits a dominant radial mode and its harmonics, plus a potential g-mode.

HD 44195 demonstrates hybrid delta Sct/gamma Dor pulsations with multiple frequencies.

Abstract

To optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The observations include both high-resolution spectroscopic and multi-colour photometric data. We present the preliminary results of the analysis of the ground-based observations of three targets. A line-profile analysis of 216 high-resolution FEROS spectra of the delta Sct star HD 50844 reveals more than ten pulsation frequencies in the frequency range 5-18 c/d, including possibly one radial fundamental mode (6.92 c/d). Based on more than 600 multi-colour photometric datapoints of the beta Cep star HD180642, spanning about three years and obtained with different telescopes and different instruments, we confirm the presence of a dominant radial mode nu1=5.48695 c/d, and detect also its first two harmonics. We find evidence for a second mode nu2=0.3017 c/d, possibly a g-mode, and indications for two more frequencies in the 7-8 c/d domain. From Stromgren photometry we find evidence for the hybrid delta Sct/gamma Dor character of the F0 star HD 44195, as frequencies near 3 c/d and 21 c/d are detected simultaneously in the different filters.