Magnetic activity of the solar-like star HD 140538

¹ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: mmittag@hs.uni-hamburg.de
² Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA
³ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
⁴ Department of Astronomy, University of Guanajuato, Guanajuato, Mexico
⁵ Sterrewacht Leiden, University of Leiden, Leiden, The Netherlands

Received: 10 April 2019
Accepted: 28 June 2019

Abstract

The periods of rotation and activity cycles are among the most important properties of the magnetic dynamo thought to be operating in late-type, main-sequence stars. In this paper, we present a S_MWO-index time series composed from different data sources for the solar-like star HD 140538 and derive a period of 3.88 ± 0.02 yr for its activity cycle. Furthermore, we analyse the high-cadence, seasonal S_MWO data taken with the TIGRE telescope and find a rotational period of 20.71 ± 0.32 days. In addition, we estimate the stellar age of HD 140538 as 3.7 Gyrs via a matching evolutionary track. This is slightly older than the ages obtained from gyrochronology based on the above rotation period, as well as the activity-age relation. These results, together with its stellar parameters that are very similar to a younger Sun, make HD 140538 a relevant case study for our understanding of solar activity and its evolution with time.