1. 체험학습
Originally we planed to visit the GwaCheon National Science Museum on November 30.
I want to change the schedule from November 30 (Tue) to November 28 (Sun). Instead, we will cancel two lectures on November 30 (Tue) and December 2 (Thu) because of the scheduling difficulty.
At the Museum, they have exhibition to experience cutting-edge astronomy such as solar system objects and exploration of extraterrestrial life.
In addition, they have been constructing the new public radio telescope equipped with a SETI (Search for extraterrestrial intelligence) spectrometer there. We aim to study ongoing SETI project in Korea through the visit.
The admission fee will be covered by the university.
We will get together in front of museum at noon on that day, and take a look at the facility till 3:00PM. 개인적인 사정이 있어 참가하기가 어려운 학생은 교수님이나 혹은 조교에게 미리 연락바랍니다.

3. Formation of Solar System

4. 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

5. Taken on November 4, 2010.

6. Protoplanetary dust disk
~1 m
Agglomeration
interaction with gas important
no gravity
~10 cm
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

7. Taken on November 4, 2010.

8. Star and planet formation belong together
The sun and the planets of our solar system 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)

9. -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)

10. 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

11. 1pc = 2x105 AU
M.Hogerheijde1998, after Shu et al. 1987

12. 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

14. Earth
Mars ©Nasa

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

18. Eagle Nebula
(M16)

20. Clearing of the remnant birth cloud

21. A star+disk appears...

22. Planets form in the disk (?)
Artist’s impression of planet formation...

23. Grinding asteriods back to dust...

24. 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.

25. Inferred surface densities
Weidenschilling 1977
A power-law approximation:

26. Formation of Kuiper belt and Oort cloud
Brett Gladmann Science 2005

27. Debris disks
After about 10 Myear most gas-rich protoplanetary disks fade away. Gas is (apparently) removed from the disk on a time scale that is shorter than normal viscous evolution.
Has been removed by accretion onto protoplanets?
Has been removed by photo-evaporation?
Dust grains are removed from the system by radiation pressure and drag (Poynting-Robertson)
Yet, a tiny but measureable amount of dust is detected in disk-like configuration around such stars. Such stars are also called ‘Vega-like stars’.

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

29. The initial growth P R I N C I P L E Start with monomers at t0 = 0
Observe aggregate mass (distribution) and structure at t > t0
P R I N C I P L E
Relative velocities due to Brownian motion, drift, gas turbulence

30. 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

31. BPCA N=2

32. BPCA N=4

33. BPCA N=8

34. BPCA N=16

35. BPCA N=32

36. BPCA N=64

37. BPCA N=128

38. BPCA N=256

39. BPCA N=512

40. BPCA N=1024

41. BCCA N=2

42. BCCA N=4

43. BCCA N=8

44. BCCA N=16

45. BCCA N=32

46. BCCA N=64

47. BCCA N=128

48. BCCA N=256

49. BCCA N=512

50. BCCA N=1024

53. Solar-system data
Weidenschilling 1977