1. NJIT Physics 320: Astronomy and Astrophysics – Lecture XIII Carsten Denker Physics Department Center for Solar–Terrestrial Research

2. December 3rd, 2003NJIT Center for Solar-Terrestrial Research The Jovian Worlds  The Giant Planets  The Jovian Moons  Io  Europa  Ganymede  Callisto  Ring System

3. 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 M Jupiter

4. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Jupiter

5. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Shoemaker-Levy 9

6. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Atmosphere

7. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Oblateness  Equatorial radius: R e = 71,370 km  Polar radius: R p = 66,750 km  Oblateness: (R e  R p ) / R e = 0.0648  First order correction term in gravitational potential:   U / m

8. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Gravitational Moments  J 2 : oblateness and moment of inertia  J 4 : mass distribution in outer regions, equatorial bulge, and planets thermal structure

9. 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 SO 2 )  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 r Jupiter  v Io = 57 km/s  potential differences of up to 600 kV and currents of up to 10 6 A

10. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Io

11. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Magnetosphere

12. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Volcanism on Io

13. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Europa

14. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Ganymede

15. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Callisto

16. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Internal Structure

17. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Saturn

18. 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 r Saturn 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

19. December 3rd, 2003NJIT Center for Solar-Terrestrial Research

20. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Atmosphere

21. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Uranus

22. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Seasons on Uranus

23. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Neptune

24. December 3rd, 2003NJIT Center for Solar-Terrestrial Research Comparison of Internal Structure

25. 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 10 th, 2003. Last chance!