The Io Plasma Torus
Volcanoes, Atmospheres, and
Magnetospheres, Oh My!
Dr. Jeff Morgenthaler
Outline
• Scientific background
– Galilean satellites
– Jovian magnetosphere
– Io plasma torus (IPT)
• Observing the IPT
• Relating the IPT to other facets of the
Jovian system
• Time allowing: other fuzzy blobs I know and
love
– Comets
– The heliosphere
Scientific background: Galilean
Satellites
• Jupiter is one of the “original” 5 planets
– Planet is Greek for “wanderer”
– Mercury, Venus, Mars, Jupiter, Saturn
• First telescopic observation by Galileo in
1610
– Showed mini Copernican system
– Four satellites
Images: Universe, Kaufmann & Freedman
Galilean
Satellite
Family
Portrait
Image source: NASA/JPL
Io
Ganymede
Europa
Callisto
Tidal heating of Io
Image source: NASA/JPL
Io is the most volcanic body in
the solar system
Pillan Patera
Prometheus
APOD 2007 February 11, Galileo data from 1997 June 28
Scientific background: Jovian
Magnetosphere
• Magnetic field: approximated by offset,
tilted dipole
Source
Scientific background: Jovian
Magnetosphere
• Magnetosphere: where a planet’s magnetic field
has more influence than the solar wind on plasma
• ~50 Rj upwind, ~100 Rj downwind
NASA/JPL
Io Plasma Torus
NASA/JPL
Observing the Io Plasma Torus
N.M. Schneider and J.T. Trauger (1995)
Neutral density filter
Narrow-band filter (e.g. S II])
Observing the Io Plasma Torus:
McMath-Pierce Solar Telescope Data
McMath-Pierce Solar Telescope
Io Torus Imager
Neutral density filter
Narrow-band filter
Guider
CCD
McMath-Pierce Solar
Telescope Facility (works at
night too)
Relating the IPT to other facets
of the Jovian system
Jovian System – Io Plasma Torus
STIS observations of Io
Io [OI] line
Example spectrum: 2002 Jan 26
Io Plasma Torus Summary
• Torus imager for portable telescopes has
been successfully deployed (Nozawa et al.
2004)
• Need to verify sky is dark enough above
Holland, MI
N.M. Schneider and J.T. Trauger (1995)
Comet Basics
Anatomy of a comet
Sun
(106 km)
Ion Tail
Dust Tail
Head
Dust (1 m)
Studying comets: remote sensing
CN coma:
X-ray emission from comets and
the solar system
• Solar wind
• Heliosphere
• Local interstellar
medium
(solar wind ion)
(cometary or interplanetary hydrogen)
Diffuse X-ray Spectrometer
What used to be thought of as
interstellar X-ray emission may
be entirely heliospheric