EPRV asteroseismology of the K dwarfs GJ 570 A and GJ 783 A with ESPRESSO. Empirical mode-amplitude scaling in tension with 3D convection simulations
Year: 2026
Type: article
Abstract: Solar-like oscillations in K dwarfs have intrinsically low amplitudes, making them challenging to detect in space-based photometry. The advent of extremely precise radial velocity (EPRV) instrumentation enables Doppler asteroseismology in the mid-K regime, providing a new opportunity to test mode-excitation and damping physics. We investigate the scaling of oscillation amplitudes with stellar parameters and assess whether 3D surface convection simulations reproduce the observed amplitude behavior. High-cadence ESPRESSO radial-velocity time series were obtained over five and six consecutive nights for the K dwarfs GJ 570 A (K4 V) and GJ 783 A (K2.5 V), respectively. We identified oscillation modes from weighted power spectra and extracted them via sine-wave fitting following spectral deconvolution. Peak mode amplitudes were measured from heavily smoothed power spectra. For comparison, we performed 3D radiative-hydrodynamical simulations including excitation and damping-rate calculations. We measured 6 modes for GJ 570 A and 24 for GJ 783 A (ell!=!0--2, and ell!=!3 for GJ 783 A). The peak radial-mode amplitudes are 2.57 ± -1 and 4.90 ± 0.81: -1 , respectively. Combined with previous Doppler detections, these results support a transition from an approximate (L/M)^0.7 amplitude scaling to a steeper, approximate (L/M)^1.5 scaling, occurring near the GK-dwarf boundary toward decreasing L/M. In contrast, 3D simulations predict an approximate (L/M)^0.9 scaling for K dwarfs, revealing tension between observations and first-principles convection models. EPRV asteroseismology extends into the mid-K regime and exposes a steep mode-amplitude scaling that our 3D convection simulations do not reproduce. This discrepancy points to missing physics in our implementation of convection–pulsation coupling and/or limitations in the adopted modeling assumptions, motivating further theoretical investigation.
Source: Astronomy and Astrophysics
Authors: T. L. Campante, Y. Zhou, Y. Li, H. Kjeldsen, R. R. Costa, A. W. Neitzel, J. H. C. Martins, A. M. Silva, V. Adibekyan, J. Gomes da Silva, J. R. Larsen, S. G. Sousa, T. R. Bedding, D. Bossini, W. J. Chaplin, E. Corsaro, M. S. Cunha, M. Deal, D. Huber, M. N. Lund, M. S. Lundkvist, T. S. Metcalfe, M. J. P. F. G. Monteiro, N. C. Santos
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: G1833668558, Shedding light on planetary system evolution and Galactic assembly with ultra-precise space-based photometry, Revelando a história evolutiva da Via Láctea com recurso à Arqueologia Galáctica, G3161872288, Instituto de Astrofísica e Ciências do Espaço, Solving long-standing challenges in stellar physics with ultra-precise space-based photometry, G6523000324, G6987963685, Probing Earth siblings throughout the Milky Way
OpenAlex ID: W7222514665