2021-04-13, 15:00: Dr. Jonathan Nichols (University of Leicester)
Dr. Jonathan Nichols
University of Leicester, UK
The auroras of Jupiter and Saturn with Hubble: recent results
Abstract: Planetary auroras are excited when energetic charged particles funnel down a planet’s magnetic field lines and impact the atmosphere. They act as a ‘TV screen’, spectacularly revealing the global dynamics of a planet’s space environment. The region of space which contains a planet’s magnetic field is the ‘magnetosphere’, within which charged particles can be accelerated to relativistic energies, and the planets of the solar system provide natural laboratories for the study of space plasmas. Jupiter’s magnetosphere is particularly important, being the solar system’s largest and most powerful, and also acting as an accessible analogue for a wide array of astrophysical bodies, e.g. inspiring theories explaining radio bursts from exoplanet systems. Jupiter’s auroras are a primary target of the NASA Juno mission, which has provided a crucial impetus for observing with the Hubble Space Telescope during the last few years. Saturn’s magnetosphere is unique, often being described as a mixture of Earth’s and Jupiter’s, and while we no longer have Cassini at the planet, there is still much we can understand from remote observations. In this seminar, results from recent programmes of observation of Jupiter’s and Saturn’s auroras will be outlined. In particular, I will describe the relation between Jupiter’s auroral intensity and the strength of the magnetospheric currents, new perspectives on enigmatic “dawn storms” and an account of what happened to Saturn’s auroras as the planet was engulfed by Jupiter’s enormous magnetotail.