Asteroseismology with TESS: Emergence of Dipole Mode Suppression from Subgiants?

Abstract Dipole mode suppression is an observed behavior of solar-like oscillations in evolved stars. This study aims to search for depressed dipole modes in giant stars using data from the Transiting Exoplanet Survey Satellite (TESS) and investigate when the suppression starts to emerge. We study a sample of 8651 evolved stars from TESS and find 179 stars with significant dipole mode depression by comparing the oscillation amplitudes of radial and dipole modes. Notably, 11 of them are located near the base of the red giant branch, indicating that mode suppression appears earlier than the point inferred in previous studies with Kepler data. These findings provide new evidence for dipole mode suppression in giant stars, particularly in subgiants.