Searching for solar-like oscillations in pre-main sequence stars using APOLLO^⋆

Can we find the young Sun?

¹ Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
e-mail: marco.muellner@student.uibk.ac.at
² INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
³ Institute of Solar-Terrestrial Physics, Siberian Branch of Russian Academy of Sciences, Lermontov Str. 126A, 664033 Irkutsk, Russia
⁴ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
⁵ South African Astronomical Observatory, PO Box 9, 7935 Observatory, Cape Town, South Africa
⁶ Southern African Large Telescope Foundation, PO Box 9, 7935 Observatory, Cape Town, South Africa
⁷ Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119234, Russia
⁸ Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia

Received: 2 October 2020
Accepted: 14 December 2020

Abstract

Context. In recent years, our understanding of solar-like oscillations from main sequence to red giant stars has improved dramatically thanks to pristine data collected from space telescopes. One of the remaining open questions focuses on the observational identification of solar-like oscillations in pre-main sequence stars.

Aims. We aim to develop an improved method to search for solar-like oscillations in pre-main sequence stars and apply it to data collected by the Kepler K2 mission.

Methods. Our software APOLLO includes a novel way to detect low signal-to-noise ratio solar-like oscillations in the presence of a high background level.

Results. By calibrating our method using known solar-like oscillators from the main Kepler mission, we apply it to T Tauri stars observed by Kepler K2 and identify several candidate pre-main sequence solar-like oscillators.

Conclusions. We find that our method is robust even when applied to time-series of observational lengths as short as those obtained with the TESS satellite in one sector. We identify EPIC 205375290 as a possible candidate for solar-like oscillations in a pre-main sequence star with ν_max ≃ 242 μHz. We also derive its fundamental parameters to be T_eff = 3670 ± 180 K, log g = 3.85 ± 0.3, v sin i = 8 ± 1 km s⁻¹, and about solar metallicity from a high-resolution spectrum obtained from the Keck archive.