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Lecture Planet Formation Topic: Overview of the standard model of planet formation Lecture by: C.P. Dullemond.

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Presentation on theme: "Lecture Planet Formation Topic: Overview of the standard model of planet formation Lecture by: C.P. Dullemond."— Presentation transcript:

1 Lecture Planet Formation Topic: Overview of the standard model of planet formation Lecture by: C.P. Dullemond

2 Standard Model 1.A star is formed, surrounded by a disk of dust and gas 2.The dust particles coagulate forming ever larger dust aggregates, rocks, boulders 3....some miracle happens... and sizes of >km are reached (as we will see later, this is a strange thing) 4.These planetesimals gravitationally interact leading to runaway growth. A planetary embryo is formed (~ 1000 km) 5.The embryo accretes further planetesimals and grows 6.Nearby embryos collide and merge to form a rocky planet 7.IF the planet continues to grow to ~ 10 Mearth, then it will attract gas from the disk and form a gas giant planet.

3 Birthplace of stars: Molecular Clouds Ophiuchus Giant Molecular Cloud (by Loke Tan)

4 Birthplace of stars: Molecular Clouds Ophiuchus Giant Molecular Cloud (by Loke Tan)

5 Forming stars from Molecular Clouds M. Bate Exeter UK Very dense Molecular Cloud: very aggressive star formation MOVIE

6 Isolated Star Formation M.Hogerheijde1998, after Shu et al. 1987

7 Observed protoplanetary disks Credit: NASA

8 Observed protoplanetary disks HST image of AB Aurigae by Carol Grady

9 The long road from dust to planets 1 m 1mm1m1m 1km1000km Gravity keeps/pulls bodies together Gas is accreted Aggregation (=coagulation) First growth phase Final phase Covers 13 orders of magnitude in size = 40 (!!) orders of magnitude in mass

10 Immanuel Kant already understood it! Der Anfang der sich bildenden Planeten ist nicht allein in der Newtonschen Anziehung zu suchen. Diese würde bei einem Partikelchen von so ausnehmender Feinigkeit gar zu langsam und schwach sein. Man würde vielmehr sagen, dass in diesem Raume die erste Bildung durch den Zusammenlauf einiger Elemente, die sich durch die gewöhnlichen Gesetze des Zusammenhangs vereinigen, geschehe, bis derjenige Klumpen, der daraus entstanden, nach und nach so weit angewachsen, dass die Newtonsche Anziehungskraft an ihm vermögend geworden, ihn durch seine Wirkung in die Ferne immer mehr zu vergrößern. Aus: Immanuel Kant Allgemeine Naturgschichte und Theorie des Himmels (1755) (thanks to Willy Kley for pointing me to this amazing citation)

11 Immanuel Kant already understood it! The start of the formation of a planet is not to be sought only in the Newtonian attractive forces. They would, for such small particles, be too slow and too weak. One would more say that the first phases of growth take place through the collision of elements that aggregate through the usual laws of cohesion, until these clumps eventuell have grown so much, that the Newtonian attractive forces, with their long range of influence, spur their growth ever further. English translation from Immanuel Kant Allgemeine Naturgschichte und Theorie des Himmels (1755) (thanks to Willy Kley for pointing me to this amazing citation)

12 So, what is this cosmic dust? Difficult to know because we have no method (yet) of collecting interstellar dust But there is interplanetary dust from evaporating comets. These Interplanetary Dust Particles are dust aggregates Collected from the stratosphere with a U2 airplane

13 Particles move......because protoplanetary disks are turbulent, and turbulent gas stirs up the dust....and because of drift (more on that during the lecture).

14 What happens when they collide? Paszun & Dominik 2009 See also Wada et al. 2009, Suyama, Wada & Tanaka 2008 Small sizes: a = 10 μm Numerical models MOVIE

15 What happens when they collide? Laboratory experiments From the laboratory of J. Blum, Braunschweig MOVIE

16 Movie from NASA

17 Next phase: Growth by gravity Thanks to Sean Raymond for lending me his movie

18 Next phase: Growth by gravity Thanks to Sean Raymond for lending me his movie MOVIE

19 Collision of two planets or moons Image credit: Don Davis ARTIST IMPRESSION

20 Collision of two planets or moons Asphaug & Reufer MOVIE

21 Accretion of smaller bodies onto big ones Stewart (2011) MOVIE

22 On to final planets Figure from C. Mordasinis lecture

23 Formation of gas giants Figure from C. Mordasinis lecture (if sufficient gas is present)

24 Formation of gas giants (if sufficient gas is present) Artists impression by Moonrunner Design National Geographic

25 Alternative GGP formation scenario Gravitational instabilities in the disk Model by Thomas Quinn

26 Alternative GGP formation scenario Gravitational instabilities in the disk Model by group of Richard Durisen

27 Planet-disk interaction & migration Kley & Nelson (2012) Annual Reviews of Astronomy & Astrophysics MOVIE

28 Planet formation synthesis models Mordasini et al. (2009) MOVIE


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