Magnetic Fields, Dynamos and Aurorae: From Brown Dwarfs to Exoplanets

NASA / ESA / J. Clarke


Scientific Motivation

Knowledge of an exoplanet’s magnetic field places constraints on the thermal state, composition, and dynamics of its interior, all of which may be difficult to determine by other means. They may also play a role in protecting planetary atmospheres from high energy particle flux from the stellar wind and beyond.

Of the various observational manifestations of exoplanetary magnetic fields that may be detectable, the most promising include 1)  auroral emission (radio, UV, OIR) resulting from an interaction between the planetary magnetosphere and the stellar wind 2) the possible detection of inflated radii of hot Jupiters due to Ohmic dissipation within the planet as the planetary magnetosphere moves through the magnetosphsere of its host star, 3) the presence of a asymmetric transit light curve due to the bow shock produced as the magnetosphere of a hot Jupiter moves through the magnetosphere of its host star, and 4) planet-phased stellar phenomena due to magnetic reconnections in the stellar magnetosphere induced by a magnetized planet.

In recent years, brown dwarfs have surprisingly been revealed as analogs of planets in their manifestation of magnetic activity, most noticeably in the detection of bright radio bursts of a similar nature to auroral planetary radio bursts as well as additional auroral emissions at optical wavelength. The benefit is twofold; brown dwarfs can serve as planetary analogs enabling efforts to more broadly understand the mechanisms by which magnetic fields can be directly detected in planets and 2) the opportunity arises to build a census of magnetic fields through the substellar and into the planetary regime, with profound impact on our understanding of dynamo theory in this parameter space.

This splinter session will focus on the observational techniques available to detect exoplanetary and brown dwarf magnetic fields, including the new generation of instruments coming on-line, as well as the theoretical insight offered by a positive detection. Discussion will focus on how best to bridge our understanding of activity across the mass gap from stars and brown dwarfs to planets.

Speaker Schedule

Session I, 2:00 - 3:40 PM

Gregg Hallinan & Evgenya Shkolnik (5): Opening Remarks

Matt Browning (20 + 5), Invited: Fully Convective Dynamos

Oleksii Kuzmychov (10 + 2) Magnetic Fields on Brown Dwarfs

Jean-Mathias Greissmeir (20 + 5), Invited:  Auroral Radio Emission on Planets and Exoplanets

Victor See (10 + 2): Modeling Exoplanetary Radio Emissions Using a Realistic Magnetic Field Geometry

Fred Adams (10 + 2): Magnetic Fields and Planetary Outflows

Poster pop (10)

3.40: Break

Session II, 4:15 - 5:45 PM

Subhanjoy Mohanty (20 + 5), Invited: Evolution in Activity and Rotation at the Bottom of the Main Sequence

Sarah Jane Schmidt (10 + 2): Chromospheric Activity on L Dwarfs

J. Sebastian Pineda (10 + 2): A Survey of Auroral Emission from Ultracool Dwarfs

Melodie Kao (10 + 2): Auroral Radio Emission from Late L and T Dwarfs: A New Constraint on Dynamo Theory in the Substellar Regime

Peter Williams (10 + 2): Pushing the limits of auroral radio emission: new results from the T6.5 dwarf 2MASS 1047+21

Panel Discussion with Speakers (15)

A Cool Stars 18 Splinter Session


Gregg Hallinan

Joseph Lazio

Evgenya Shkolnik