Volume 628, August 2019
|Number of page(s)||7|
|Section||Stellar structure and evolution|
|Published online||14 August 2019|
INAF – Osservatorio Astrofisico di Catania, Via S. Sofia, 78, 95123 Catania, Italy
e-mail: firstname.lastname@example.org, email@example.com
2 Institute of Astrophysics, FORTH, 71110 Heraklion, Greece
3 Department of Physics, University of Crete, 70013 Heraklion, Greece
4 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
5 School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
Accepted: 2 July 2019
We present further evidence of acoustic oscillations in the slowly rotating overactive G8 sub-giant EK Eri. This star was observed with the 1m Hertzsprung SONG telescope at the Observatorio del Teide for two different runs of 8 and 13 nights, respectively, that were separated by about a year. We determined a significant excess of power around νmax = 253 ± 3 μHz in the first observing run and were able to determine a large separation, Δν = 16.43 ± 0.22 μHz. No significant excess of power was instead detected in a subsequent SONG observing season, as also supported by our analysis of the simultaneous TESS photometric observations. We propose a new amplitude-luminosity relation in order to account for the missing power in the power spectrum. Based on the evolutionary stage of this object, we argue that a standard α2Ω dynamo cannot be excluded as the possible origin for the observed magnetic field.
Key words: stars: activity / starspots / stars: rotation / asteroseismology / magnetohydrodynamics (MHD) / stars: individual: EK Eri
A table of the radial velocities is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A106
© ESO 2019
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