Coronal activity cycles in action - X-rays from alpha Centauri A/B

Abstract

We report on the coronal activity cycles of our stellar neighbors alpha Centauri A/B. The binary has been monitored with XMM-Newton since 2002 to study the long-term evolution of coronal activity evolution in X-rays. The solar analog alpha Cen A was clearly detected early in the program, but virtually faded away from XMM's detectors view around 2005. After remaining nearly a decade in a state of coronal weakness, we now detect a clear re-brightening of its corona. The secondary alpha Cen B dominates the X-ray emission at most times and more than a full cycle is covered for this star. A new X-ray maximum was observed around 2012 that is again followed by gentle dimming over the recent years. The temporal evolution of the X-ray emission can be well understood, in analogy to the 11 year solar-cycle, by coronal activity cycles with different amplitudes and periods operating in both stars.

Proceedings of Cool Stars 19 (The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, edited by G.A. Feiden); 3 pages, 5 figures