From Stellar Activity to Exoplanetary Environments (speaker: Cecilia Garraffo, CfA)

Tuesday, October 31, 2:00pm
NE83-530A (The Great Room)

Stellar activity is known to be controlled by rotation. Observations of young open clusters have revealed a bimodal distribution of the rotation periods of solar-like stars that has proven difficult to explain under the existing rubric of magnetic braking.  We have found that magnetic complexity can play an important role in controlling stellar spin-down rates, and provides a natural physical basis for the rapid transition between fast and slow rotation modes.  Relevant applications include the spin down of young stars and the orbital evolution of cataclysmic variables.  The secular evolution of magnetic activity is also key to understanding the space weather of exoplanets.  In this talk I will discuss how magnetic activity scales with rotation and, therefore, with age, its effects on exoplanetary environments with special reference to the situation of Proxima b and TRAPPIST-1, and how this new spin-down prescription can provide a natural explanation for problems such as the CV period gap.

Upcoming meetings:

Thu  9 Nov 2:00pm/NE83

Thu 16 Nov 2:00pm/Marlar

   Zhenlin Zhu/ Nanjing University (via Shuo) "A Galactic center X-ray point source catalogue"

Thu 30 Nov 2:00pm/Marlar

   Yuanyuan Su / CfA: TBA