Travis S. Metcalfe
High Altitude Observatory

Abstract
The Mount Wilson Ca HK survey revealed magnetic activity variations in a large sample of solar-type stars with timescales ranging from 2.5 to 25 years. This broad range of cycle periods is thought to reflect differences in the rotational properties and the depths of the surface convection zones for stars with various masses and ages. In 2007 I initiated a long-term monitoring campaign of Ca II H and K emission for a sample of 58 southern solar-type stars to measure their magnetic activity cycles and their rotational properties when possible. I will provide an overview of the program, including an update on our discovery of the shortest activity cycle ever measured for a solar-type star (1.6 years in the exoplanet host star iota Horologii), and I will preview the short-term variations that we have identified in several other targets.

2012 October 03, 13:30

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto