Magnetic variability in the young solar analog KIC 10644253

Observations from the Kepler satellite and the HERMES spectrograph

¹ Laboratoire AIM, CEA/DRF-CNRS, Université Paris 7 Diderot, IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette, France
e-mail: david.salabert@cea.fr
² Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
³ Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, 38205, La Laguna, Tenerife, Spain
⁵ CNRS, Institut de Recherche en Astrophysique et Planétologie, 14 avenue Édouard Belin, 31400 Toulouse, France
⁶ Université de Toulouse,UPS-OMP, IRAP, 31400 Toulouse, France
⁷ Universidade Federal do Rio Grande do Norte, UFRN, Dep. de Física, DFTE, CP1641, 59072-970 Natal, RN, Brazil
⁸ Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
⁹ High Altitude Observatory, National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307-3000, USA
¹⁰ Department of Physics, Montana State University, Bozeman, MT 59717-3840, USA
¹¹ Space Science Institute, 4750 Walnut street Suite#205, Boulder, CO 80301, USA

Received: 16 December 2015
Accepted: 29 February 2016

Abstract

The continuous photometric observations collected by the Kepler satellite over 4 yr provide a wealth of data with an unequalled quantity and quality for the study of stellar evolution of more than 200 000 stars. Moreover, the length of the dataset provides a unique source of information for detecting magnetic activity and associated temporal variability in the acoustic oscillations. In this regards, the Kepler mission was awaited with great expectations. The search for the signature of magnetic activity variability in solar-like pulsations still remained unfruitful more than 2 yr after the end of the nominal mission. Here, however, we report the discovery of temporal variability in the low-degree acoustic frequencies of the young (1 Gyr-old) solar analog KIC 10644253 with a modulation of about 1.5 yr with significant temporal variations for the duration of the Kepler observations. The variations agree with the derived photometric activity. The frequency shifts extracted for KIC 10644253 are shown to result from the same physical mechanisms involved in the inner subsurface layers as in the Sun. In parallel, a detailed spectroscopic analysis of KIC 10644253 is performed based on complementary ground-based, high-resolution observations collected by the HERMES instrument mounted on the Mercator telescope. Its lithium abundance and chromospheric activity 𝒮 index confirm that KIC 10644253 is a young and more active star than the Sun.