Photometric periods of HN Peg from multichannel analysis^*

¹ Astronomy Division, Department of Physical Sciences, PO Box 3000, 90014 University of Oulu, Finland
² Frankenallee 201, 60326 Frankfurt/Main, Germany

Received: 9 October 2000
Accepted: 22 November 2004

Abstract

We applied the method of three-stage weighted multichannel period analysis (MPA) to photometric observations of HN Peg obtained in 1992–99. We detected two periods: the longer one stayed almost constant near 51 but appeared only during the observing seasons in 1993–98, while the shorter one was present for all observing seasons, having fluctuations within .
If the two periods are interpreted as caused by differential rotation, we may have detected two distinct latitude zones of spot activity, one where spots were confined to within a very narrow range of latitude, and another where the latitude range may be somewhat broader. The existence of two latitude zones of activity in this young solar analogue closely matches what is seen in the Sun. However, the presence of two periods may also be caused by long-lived active areas moving in longitude.
We use HN Peg as a test case for our new MPA statistical method. Because of the limited quality of the data and the complexity of stellar activity our results are tentative, leaving space also for other interpretations.