1. 5. Formation of Solar System
Big bang
Nuclear fusion in stars
Supernova nucleosynthesis
Planetary formation
Current Solar System
5. Formation of Solar System
May 21, 2012
외계행성과 생명

2. Proverb 티끌모아 태산 Many a little makes a mickle.
Light gains make heavy purses.

3. Chronology of the Universe
13.7 Gyr
Big bang; formation of the elements H and He
13.4 Gyr
First stars and galaxies; first supernova explosions produce the heavy elements (C,N,O,Si,Fe,…)
12 Gyr
Formation of the milky way
4.567 Gyr
Formation of the solar system; at this point in time the interstellar medium has been enriched with 1% heavy elements
Formation of the earth and the moon
4.5 Gyr
Layer structure of the earth
4.45 Gyr
Solid earth crust
4.4 Gyr
Early ocean
4.2 Gyr
Plate tectonics
4 Gyr
Earth’s magnetic field
Origin of life
>3.5 Gyr
Formation of oxygen-rich atmosphere; formation of ozone
2.3 Gyr
0 Gyr
Today

4. Star and planet formation belong together
The sun and the planets formed at the same time,
and from the same material reservoir on the basis of these facts:
Elementary abundances
Age of the meteorites = age of the sun, i.e Gyr
Parallel angular momentum of sun and planets
(Obliquity of the sun to ecliptic = 7.25 deg)
e.g. 238U  206Pb (4.468Gyr)
235U  207 Pb in

5. -Solar 　　 Anders & Grevesse (1989), Geochim. Cosmochim. Acta. 53, 197
-Halley’s dust　Jessberger et al. (1988), Nature 332, 21, 691
-Comet　gas Swamy, in Physics of Comets
-Chondrite Andrers & Ebihara, Geochim. Cosmochim. Acta. 46, 2363 (1982)

6. Star formation – an overview
Molecular cloud
Star formation – an overview
© GEO, after Shu et al. 1987
Formation of gas-dust disk
“Clumping” of the dust
Formation of the sun by radial transport of matter
Formation of isolated planets

7. Protoplanetary dust disk
~1 m
Agglomeration
interaction with gas important
no gravity
~10 cm
Coulomb force
Gravitational force
Planetesimals
~10 km
Accretion of planetesimals
no interaction with gas
gravity dominates
Terrestrial planets
~10,000 km
Gas accretion
gravity dominates
if escape velocity > thermal velocity (i.e. larger than Earth masses), migration potentially important
Gas planets
~100,000 km
Planetesimals = Minute planets

9. 1pc = 2x105 AU
M.Hogerheijde1998, after Shu et al. 1987

10. Stars are born deep in very cold dark (optically thick) clouds
Stars are born deep in very cold dark (optically thick) clouds. Their birth is ‘secret’: not visible at optical wavelength. Infrared telescopes can penetrate through these clouds and witness the first signs of life from a protostar.

11. Zoom-in M16 (Eagle) Milky Way M17 (Horseshoe) M8 (Lagoon) Hale-Bopp
Jupiter
M16 (Eagle)
M17 (Horseshoe)
M8 (Lagoon)
Milky Way
Hale-Bopp

14. Eagle Nebula
(M16)

16. A star + disk appears...

17. 1pc = 2x105 AU
M.Hogerheijde1998, after Shu et al. 1987

18. What have we learned so far?
The sun and our planets formed concurrently billion years ago.
Extrasolar planetary systems can be similar to or different from the solar system.
Dust plays a decisive role in the formation of the planets.
The lifetime of protoplanetary disks, the birthplaces of planets, is a few million years.

19. Debris disks Beta-Pictoris
Age: 100 Myr (some say 20 Myr)
Dust is continuously replenished by collisions between planetesimals. Disk is very optically thin (and SED has infrared excess).

20. Consider the simplest cases
BPCA
Ballistic Particle-Cluster Agglomeration ⇓
ballistic hit-and-stick impacts of single dust particles into growing dust agglomerate
BCCA
Ballistic Cluster-Cluster Agglomeration
ballistic hit-and-stick collisions between equal-mass dust agglomerates
i = 1,024
i = 1,024

21. BPCA N=2

22. BPCA N=4

23. BPCA N=8

24. BPCA N=16

25. BPCA N=32

26. BPCA N=64

27. BPCA N=128

28. BPCA N=256

29. BPCA N=512

30. BPCA N=1024

31. BCCA N=2

32. BCCA N=4

33. BCCA N=8

34. BCCA N=16

35. BCCA N=32

36. BCCA N=64

37. BCCA N=128

38. BCCA N=256

39. BCCA N=512

40. BCCA N=1024

42. Bradley et al. 2005