1. The formation of stars and planets Day 5, Topic 3: Migration of planets and Outlook... Lecture by: C.P. Dullemond

2. Three types of migration Type I: low mass planets Type II: high mass planets Type III: rare type II variant

3. Type I migration Planet’s gravity launches spiral waves in disk These spiral waves exert torque on planet: –Inner spiral wave pushes planet outward –Outer spiral wave pushes planet inward Outer spiral wave wins: inward migration

4. Type I migration by Frederic Masset www-star.qmul.ac.uk/~masset/

5. Type I migration Time scale of inward type I migration (1 solar mass star): Review Thommes & Duncan in “The Formation of Planets” 2005 3-D estimates: 10 5...10 6 (Tanaka et al. 2002)

6. Gap opening Hill sphere: sphere of gravitational influence of planet: If Hill radius larger than h of disk: disk can be regarded as thin compared to potential. This happens for massive enough planets. Planet will affect structure of the disk. P. Ciecielag

7. Effective potential, Lagrange points r1r1 r2r2 Effective potential in the co-rotating frame: centrifugal kinetic energy Example: M 2 /M 1 =0.1 L1L1 L2L2 L3L3 L4L4 L5L5

8. Effective potential, Lagrange points r1r1 r2r2 Effective potential in the co-rotating frame: centrifugal kinetic energy Example: M 2 /M 1 =0.01 L1L1 L2L2 L3L3 L4L4 L5L5

9. Trojans of Jupiter

10. Motion of gas / particles in horseshoe

11. Gap opening by Frederic Masset www-star.qmul.ac.uk/~masset/

12. Type II migration Massive planet opens a gap Accretion in the disk is stopped by the gap –If the disk is massive enough: accretion continues, simply by pushing the planet inward. Planet is locked to the disk accretion. Type II migration –If the disk is not massive enough: planet will not migrate. Inner disk will deplete. Three-dimensional models: accretion can still proceed somewhat by flowing in 3-D past the planet.

13. Transition from I to II and gap opening by Frederic Masset www-star.qmul.ac.uk/~masset/

14. Type III migration (run-away migration) Masset & Papaoloizou

15. Type III migration (run-away migration) Masset & Papaoloizou

16. Type III migration (run-away migration) If planet initially moves inward: –Some inner disk material enters horseshoe, gets flung to outer orbit of horseshoe by planet. Planet loses angular momentum. –Some horseshoe material enters outer disk, does not get flung back to inner orbit of horseshoe. –Netto: one-sided asymmetric angular momentum transport from planet to disk: inward push! Run-away! If planet initially moves outward: Same thing, but the other way: planet is pushed outward. Also run- away!

17. Type III migration (run-away migration) www-star.qmul.ac.uk/~masset/ by Frederic Masset Note: this movie has opposite rotation as discussion above.

18. Why do planets exist everywhere? Migration should have depleted all planets What about bandwagon approach (form planets all the time, lose most of them via migration, but when disk dissipates some are left)? –Problem: Need plenty of solid disk material to form a planet –Problem: First make rocky core, then accrete gas. This process takes longer than migration time scale. Problem of migration is one of main open questions of planet formation!

19. How to planets get in resonance? G. Bryden

20. Stopping migration with a resonance Masset & Snellgrove

21. Outlook

22. Field of star- and planet formation more lively than ever! New telescopes give us unprecedented view of disks: –Spitzer Space Telescope (infrared) –Very Large Telescope interferometer (infrared) –ALMA (submillimeter) >= 2010 –Herschel (far-infrared) >= 2007 Theory/lab: –Computers are now powerful enough to model the growth from dust to planets –Laboratory experiments measure sticking and collision properties of particles

23. Outlook Very Large Telescope: Infrared Interfero- metry Resolving the earth forming regions of disks (in operation)

24. Outlook Herschel Space Observatory (far-infrared/submillimeter) Looking for water in extrasolar (pre-)planetary systems

25. Outlook Atacama Large Millimeter Array (ALMA) Chemistry, small scale disk structure, large grain dust population

26. Outlook Planet-hunting is hot! –Space missions will even be able to detect Earth-like planets! DARWIN / TPF –We may even analyze their atmospheres!!! (life??)

27. Outlook Darwin/TPF: hunting for other ‘Earths’

28. Outlook Detection of possible life on extrasolar Earth-like planets