Brian Fields UIllinois 2021/3/3 | When Stars Attack! Near-Earth Supernova Explosions Revealed by Deep-Ocean and Lunar Radioactivity
From Federica Bianco on September 14th, 2021
Magnetic early-type stars are characterized by the presence of large-scale surface magnetic fields that lead to the formation of a magnetosphere around them. This magnetosphere is the site of several phenomena that generate radiation over a wide range of the electromagnetic spectrum. Among them, the most recently discovered (and hence least understood) phenomenon is the generation of coherent radio emission that is observed as periodic pulses over sub-GHz to GHz frequencies. We recently coined the name of 'Main sequence Radio Pulse emitter’ (MRP) for the hot magnetic stars that can emit radio pulses. The mechanism by which they produce radio pulses is the electron cyclotron maser emission (ECME), which is also the mechanism behind the Earth’s auroral kilometric emission. In my talk, I will describe the unique characteristics of MRPs that set them apart from other ECME emitting objects. The highlight of my talk will be the different information which one can extract about the host star from the observation of ECME. This includes (but not limited to) inference of rotation period evolution, and estimation of plasma density and distribution in the stellar magnetosphere. In addition, I will also talk about radio flares and 'giant pulse’ that we have recently observed from a MRP at sub-GHz frequencies. I will discuss possible sources of these flares and their implication about the magnetic field-stellar wind interaction.
Wednesday, March 3