Abstract:
The number of sunspots on the Sun follows an 11-year cycle. We are currently at solar minimum, and the minimum has proved to be longer-lasting than expected, prompting some speculation about the possibility of a new extended minimum. However, at the end of October, the Sun briefly woke from its slumber and produced a small but extremely vigorous sunspot region: "active region 11029". Sunspot/active regions are the sites of production of solar flares, which are magnetic explosions in the Sun's outer atmosphere. Active region 11029 produced a remarkable sequence of small solar flares during a one-week transit of the Sun's disk, and the events were observed in isolation due to the absence of other activity. Solar flares usually follow a featureless power-law size distribution (the number of flares per unit size varies as an inverse power of the flare size, where size is a proxy for energy). However, active region 11029 appeared to break this statistical rule. The time history of flare production in the region is presented, together with discussion about how the observed flare statistics provide insight into the underlying processes of energy storage and release in solar flares. Bayesian methods of data analysis are also demonstrated.

Location:
Slade Lecture Theatre
School of Physics A28
Physics Road
University of Sydney
Enquiries: Bruce Yabsley (9351 5970) or

Cake will be provided from 3:00pm in the lecture theatre.

• USyd Applied Maths Seminar
• UNSW School of Physics
• Australia Telescope National Facility
• Anglo-Australian Observatory