Detection of solar-like oscillations in the bright red giant stars γ Piscium and θ1 Tauri from a 190-day high-precision spectroscopic multi-site campaign⋆

摘要: Context. Red giants are evolved stars which exhibit solar-like oscil lations. Although a multitude of have been observed with space telescopes, only handful red-giant were targets spectroscopic asteroseismic observing projects. Aims. We search for oscillations in the two bright red- giant starsγ Psc andθ 1 Tau from time series ground-based spectroscopy and determine frequency excess oscillation powerνmax mean large separation �ν both stars. Seismic constraints on stellar mass radius wi ll provide robust input modelling. Methods. The radial velocities ofγ monitored 120 190 days, respectively. Nearly 9000 spectra obtained. To reach accurate velocities, we used simultaneous thorium-argon iodine-cell calibration our optical spectra. In addition to spectroscopy, acquired VLTI observations an independent estimate radius. Also 22 days ofθ MOST-satellite analysed. Results. analysis velocity data γ revealed power around 32µHz 4.1±0.1µHz.θ exhibits 90µHz, 6.9±0.2µHz. Scaling relations indicate that is star about M⊙ 10 R⊙.θ appears be massive 2.7 R⊙. found modulated scales much longer than periods. Conclusions. estimated radii seismology agreement interferometric also estimates based photometric data. While results dynamical parallaxes, find lower what given literature. long periodic varia bility agrees expected rotational modulation.