Details

Autor(en) / Beteiligte

• Mittag, M.
• Schmitt, J. H. M. M.
• Hempelmann, A.
• Schröder, K.-P.

Titel

Discovery of short-term activity cycles in F-type stars

Ist Teil von

• Astronomy and astrophysics (Berlin), 2019, Vol.621, p.A136

Ort / Verlag

Heidelberg: EDP Sciences

Erscheinungsjahr

2019

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Previous studies have revealed a 120 day activity cycle in the F-type star τ Boo, which represents the shortest activity cycle discovered until now. The question arises as to whether or not short-term activity cycles are a common phenomenon in F-type stars. To address this question, we analyse S-index time series of F-type stars taken with the TIGRE telescope to search for periodic variations with a maximal length of 2 years using the generalised Lomb-Scargle periodogram method. In our sample, we find four F-type stars showing periodic variations shorter than one year. However, the amplitude of these variations in our sample of F-star type stars appears to be smaller than that of solar-type stars with well-developed cyclic activity, and apparently represents only a part of the total activity. We conclude that among F-stars, the time-behaviour of activity differs from that of the Sun and cooler main sequence stars, as short-term cyclic variations with shallow amplitude of the cycle seem to prevail, rather than cycles with 10+ years periods and a larger cycle amplitude.