Magnetic activity of the solar-like star HD 140538

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${}_{\mathrm{MWO}}$-index time series composed from different data sources for the solar-like star HD 140538 and derive a period of 3.88$\pm$0.02 yr for its activity cycle. Furthermore, we analyse the high-cadence, seasonal S${}_{\mathrm{MWO}}$ data taken with the TIGRE telescope and find a rotational period of 20.71$\pm$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.

7 pages, 6 figures, accepted for publication in A&A