physics 320: astronomy and astrophysics – lecture xiii
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Physics 320: Astronomy and Astrophysics – Lecture XIII. Carsten Denker Physics Department Center for Solar–Terrestrial Research. The Jovian Worlds. The Giant Planets The Jovian Moons Io Europa Ganymede Callisto Ring System. - PowerPoint PPT PresentationTRANSCRIPT
NJIT
Physics 320: Astronomy and Astrophysics – Lecture XIII
Carsten Denker
Physics DepartmentCenter for Solar–Terrestrial Research
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
The Jovian Worlds
The Giant PlanetsThe Jovian Moons
Io Europa Ganymede Callisto
Ring System
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
The Giant Planets
Jupiter, Saturn, Uranus, and Neptune = 99.5% of the entire mass of the planetary system
Galileo Galilei 1610 Galilean moons and Saturn’s ring (telescope)
Pioneer 10/11 and Voyager ½
Galileo and Cassini-Huygens
Contribution of degenerate electron pressure
Brown dwarfs must have masses less than about 80 MJupiter
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Jupiter
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Shoemaker-Levy 9
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Atmosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Oblateness
Equatorial radius: Re = 71,370 km
Polar radius: Rp = 66,750 km
Oblateness: (Re Rp) / Re = 0.0648
First order correction term in gravitational potential: U / m
2 4
2 2 4 4( ) 1 cos cose eR RGMJ P J P
r r r
0
22
4 24
Legendre Polynomia
(cos ) 1
1(cos ) 3cos 1
21
(cos ) 34cos 30cos 38
ls
P
P
P
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Gravitational Moments J2: oblateness and
moment of inertia J4: mass distribution in
outer regions, equatorial bulge, and planets thermal structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
The Jovian Moons
Galilean moon: Io, Europa, Ganymede, and Callisto
Rock increase of water-ice crust (volatiles)
Formation of moons linked to formation of Jupiter itself
Hot Jupiter evaporation of volatiles on the closer moons
Tidal interactions volcanism
Volcanism similar to geysers (sulfur and sulfur dioxide SO2)
Resonance in orbits of Io, Europa, and Ganymede: 1:2:4 ratio of orbital periods
Galilean moons are located inside Jupiter’s magnetosphere (210 times rJupiter
vIo = 57 km/s potential differences of up to 600 kV and currents of up to 106 A
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Io
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Magnetosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Volcanism on Io
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Europa
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Ganymede
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Callisto
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Internal Structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Saturn
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Ring Systems
Cassini division Encke gap Thousands of ringlets F ring is very narrow and
appears to be braided Ring extend about 5
rSaturn and are very thin ( 10 m, ripples 1 km)
Optical depth of ring system between 0.1 and 2
Partially inelastic collisions keep rings thin
Ring particles are small, a few centimeters to several meters
Rings are highly reflective (albedos in the range from 0.2 to 0.6)
Ring systems of Jupiter, Uranus, and Neptune
Keplerian shear Shepherd moons Orbital resonance Spiral density waves Poynting-Robertson
effect
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Atmosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Uranus
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Seasons on Uranus
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Neptune
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Comparison of Internal Structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
Homework Class Project Continue improving the PPT presentation. Use the abstract from the previous
assignment as a starting point for a PowerPoint presentation.
The PPT presentation should have between 5 and 10 slides.
Bring a print-out of the draft version to the next class as a discussion template for group work
Homework is due Wednesday December 10th, 2003. Last chance!