BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The Magnetic Fields of Mercury\, Ganymede\, and Saturn: Progress\,
  Challenges\, and Opportunities (Invited speaker) - Hao Cao (University of
  California\, Los Angeles)
DTSTART:20220913T090000Z
DTEND:20220913T094500Z
UID:TALK177482@talks.cam.ac.uk
DESCRIPTION:\n\n\n\nThe solar system offers a diverse group of planetary m
 agnetic fields. While prevailing in all four giant planets\, present-day l
 arge-scale magnetic fields are not common among terrestrial planets and mo
 ons. Mercury is the only terrestrial planet other than the Earth that harb
 ors a planetary-scale magnetic field\, while Ganymede is the only moon tha
 t manages to maintain a large-scale magnetic field at present.\nIn the fir
 st part of this talk\, I will present a comparative review of the magnetic
  fields of Mercury and Ganymede. Three defining features of Mercury&rsquo\
 ;s magnetic field are 1) its relatively weak strength (~1% of the Earth&rs
 quo\;s surface magnetic field)\, 2) its strong north-south asymmetry\, and
  3) its axial dominance. Ganymede possesses a surprisingly strong axial-di
 pole-dominant magnetic field. However\, our understanding of the character
 istics of Ganymede&rsquo\;s core field beyond the dipole component is limi
 ted due to the sparse coverage of existing observations and the likely ele
 ctromagnetic induction signal from the subsurface ocean. There remain sign
 ificant uncertainties in our understanding of core properties of Mercury a
 nd Ganymede (e.g.\, the composition\, the existence and extent of iron sno
 w zones\, and the electrical conductivity)\, which directly impact our inf
 erence of the dynamo mechanism responsible for their magnetic fields.\nIn 
 the second part of this talk\, I will briefly summarize recent observation
 s of the Saturnian magnetic field and the challenges to understand its ori
 gin. Saturn&rsquo\;s magnetic field is highly axisymmetric (with a dipole 
 tilt less than 0.007 degrees) yet rich in spatial scales. With smooth tran
 sitions in material properties from deep interior to surface\, Saturn&rsqu
 o\;s dynamo is expected to be strongly coupled to dynamics in the molecula
 r envelope. Zonal flow magnetic field interaction in the transition region
  likely plays an important role in the truncation of deep zonal flows and 
 the generation of small-scale axisymmetric magnetic field. Different types
  of stable stratification have been proposed for the interior of Saturn\, 
 e.g.\, an extensive helium rain layer and a large diffuse core\, which lea
 ves not much space for the traditional convective dynamo to operate.\nI wi
 ll conclude this presentation with an outlook for upcoming observations an
 d a summary of key open questions concerning the origin of planetary magne
 tic fields.\n\n\n\n
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR