The fine scales of solar chromospheric flares

A solar flare is an intense but short-lived release of energy from the Sun's magnetically-dominated atmosphere, resulting in the acceleration of non-thermal particles, plasma heating, and radiation across the entire electromagnetic spectrum. Most energy released is radiated by the solar chromosphere, giving rise to bright, highly structured 'footpoints' and 'ribbons' of chromospheric emission. The big picture of a solar flare, and the significance of flare ribbons in the global reconnection scenario, is well established, but high-resolution observations show fine spatial, temporal and spectral structure which can be probed to further explore flare physics. In this talk I will overview the basic framework of a solar flare and its development in the solar chromosphere, highlighting some examples of how fine scales are being used to investigate energy release and transport. I will focus on results from the IRIS spacecraft in the UV, and a newly-opened window on flares in the mid-infrared.

Late-type stars and their close-by planets: aspects of their magnetic interactions

Stars interact with their close-by planets through the gravitational and the magnetic fields as well as with their radiation. After a brief introduction to those different kinds of interactions, I shall review some observational clues of magnetic star-planet interactions considering data obtained in the optical, X-ray, and radio domains. Some analytical models, based on a stellar force-free coronal field or the excitation of Alfven waves by an orbiting planet, will be presented to explore the energetics of the interactions. Some numerical models will be discussed to show their advantages and drawbacks in predicting the interactions. A selection of preliminary results on the impact of star-planet magnetic interactions on the future direct imaging of exoplanets will be presented.

Speaker: David Hogg (NYU/CCA)
Title: TBD