CANCELED -- Imaging All the Sky All the Time in Search of Radio Exoplanets (Speaker: Gregg Hallinan, CalTech)
Due to the weather forecast for March 14, we have canceled this colloquium and hope to reschedule this talk during our fall series.
All the magnetized planets in our solar system, including Earth, produce bright emission at low radio frequencies, predominantly originating in high magnetic latitudes and powered by auroral processes. It has long been speculated that similar radio emission may be detectable from exoplanets orbiting nearby stars, which would provide the first direct confirmation of the presence, strength and extent of exoplanetary magnetospheres, as well as informing on their role in shielding the atmospheres of potentially habitable exoplanets. Despite 4 decades of observations, no detection has been achieved. Surprisingly, however, brown dwarfs have been found to produce both radio and optical emissions that are strikingly similar to the auroral emissions from solar system planets, albeit 10,000 times more luminous, bolstering the continued search for similar emission from exoplanets. In the case of the latter, the absence of detection thus far may simply be due to the highly variable nature of the radio emission. The auroral radio emission from Earth can increase by three orders of magnitude during a geomagnetic storm and a similar dependence on local space weather conditions can be assumed for exoplanets, requiring dedicated monitoring of stellar systems to enable detection. I will discuss the auroral radio emission from exoplanets and brown dwarfs and introduce a new radio telescope, consisting of 352 antennas spaced across 2.5 km, that images the entire viewable sky every ten seconds at low radio frequencies, thereby monitoring thousands of stellar systems simultaneously in the search for radio emission from exoplanets.
Host: Michael McDonald