Lecture by CP Dullemond Institute for Theoretical Astrophysics Heidelberg University Image Credit NASA The Big Questions After C Mordasini gt 10 billion galaxies in the Universe 100 billion stars in each ID: 372410
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Slide1
The Formation of Planets
Lecture by C.P. Dullemond
Institute for Theoretical Astrophysics
Heidelberg University
Image
Credit
: NASASlide2
The Big Questions
After C. Mordasini
> 10 billion galaxies in the Universe
100 billion stars in each
galaxy
several (?) planets around
each star
how many harbour life?
How did we come about?
Are we alone in the Universe?Slide3
What is a planet?
Originally: „wandering star“
The „star“ made trajectories with „epicycles“ across the skySlide4
What is a planet?
Rocky planet:
Is round
Has solid surfaceSometimes an atmosphere, tooIn rare cases it has liquid waterConsists mostly of rock (silicates) in the outer parts and iron+nickel in the core
All known rocky planets orbit a starSlide5
What is a planet?
Gas giant planet:
Is round
Has no solid surfacePresumably has rocky coreConsist mostly of Hydrogen and Helium
Mass >> Mearth
Most known gas giant planets orbit a star
(Just this week the first confirmed free-floating planet was announced:
PSO J318.5-22)Slide6
What is a planet?
Ice giant planet:
Is roundHas
no solid surfaceAtmosphere is Hydrogen and HeliumBut interior is volatile elementsPresumably has rocky core tooMearth < M < MgasgpAll known ice giant planets orbit a starSlide7
Immanuel Kant
Our Solar System
Why do all planets lie in the same plane?
Why do they all have circular orbits?
Why do they rotate all in the same direction?
Immanuel Kant and Pierre-Simon Laplace
realized that they must have formed from a
disk around the young sun. Today we call this
the „solar nebula“ or more general: a
„protoplanetary disk“.Slide8
Today we
know
that protoplanetary disks existSlide9
Today we
know
that protoplanetary disks existSlide10
Constellation
“
Orion
”
Today we
know
that protoplanetary disks existSlide11
Constellation
“
Orion
”
Today we
know
that protoplanetary disks existSlide12
Today we
know
that protoplanetary disks existSlide13
Hidden behind the far-
end of the disk is the star
= 500 AU
= 16x Distance Sun-Neptune
Today we
know
that protoplanetary disks existSlide14
The ingredients of planet formation
Image
Credit
: NASAProtoplanetary Disk
Dust (the raw material
of rocky planets)
Comets (icy planetesimals)
Asteroids (rocky planetesimals)
Massive planets open up gaps in the disk
(planet-disk interaction & disk hydrodyamics)
Planets grow through accretion
of planetesimals
Dust coagulates to larger rocks,
and eventually to planetesimals
Collisions are
the
driving process
Planets interact
gravitationally:
N-body dynamicsSlide15
This lecture:...focuses on the question „how did we come about?“, or more concretely: „how do planets form?“Active research area: Many of the main questions not yet solved.We will discuss the standard picture (for as much as a „standard picture“ exists at all)We will focus on physicsWe will discuss mostly the formation of rocky (earth like) planets, but also to some extent of gas giant planets.Slide16
Goals:Brief introduction to / reminder of:Properties of the Solar System
(the planets, asteroid belt, Kuiper belt, comets, meteorites)Properties of Extrasolar Planetary Systems
(methods of detection, current statistics)Glance over the standard model of planet formation
Sharpening our tools:Hydrodynamics and magnetohydrodynamicsRadiative transferSlide17
Goals:Learn the physics of planet formation (part 1):Protoplanetary disks
(formation, structure, evolution, radiative transfer, hydrodynamics, magnetohydrodynamics, turbulence, vortices, chemistry, planet-disk interaction)Growth of initial dust aggregates (“molecular” dynamics models, Smoluchowski equation: how to cover 40-orders of magnitude, processes: sticking, shattering, restructuring, porosity, evaporation/condensation, motion: drift, turbulence)
Planetesimal formation (particle trapping, Roche density, Goldreich & Ward model, Kelvin-Helmholz turbulence, gravoturbulent PF, streaming instabilities)
Restricted 3-body problem (Hill sphere, coorbital horseshoe region, Lagrange points, Jacobi integral, Tisserand relation, zero-velocity orbits, epicyclic motion, viscous stirring, chaos theory)Oligarchic growth of rocky planets (gravitational focusing, runaway growth, viscous stirring & dynamical friction, thermodynamic description, self-regulation leading to oligarchy)
Mean motion resonances
(resonant angles, libration, width of resonances, stability/instability)Slide18
Goals:Learn the physics of planet formation (part 2):Internal structure of rocky bodies
(gravitational compaction, internal radioactive heating, differentiation, tectonics)Meteorite parent bodies
(CAIs, chondrules, matrix, age determination)Gas giant planet formation (initial planetary core with acquired atmosphere, growth through accretion of planetesimals, collapse of atmosphere and runaway gas accretion, cooling problem, angular momentum problem, circumplanetary disk, origin of Saturn’s rings and giant planet moons)
Planet-disk interaction & migration (spiral wave excitation and the resulting Lindblad torques, coorbital torques, saturation, role of disk viscosity, role of heating/cooling, gap opening, type I, II and III migration, migration as a “tool” to create hot Jupiters, to drive planets into resonances, migration traps)Planetary collisions (fully destructive collisions, hit-and-run collisions, mantel stripping, formation of binary and contact-binary bodies, mergers)
Debris disks
(collisional cascades, Poynting Robertsen drag, blow-out)
Long-term dynamic evolution
(the “Nice” model, Kozai cycles, stability)Slide19
OrganizationWhen: Each Monday, 14:15-16:00Where: Philosophenweg 12, kleine HörsaalWeb: http://www.ita.uni-heidelberg.de/~dullemond/lectures/planetformation_2013/Moodle: via the web page (password=„Roche“)Registration: Please register on the Moodle, so that you are always up to date.
Lecture material will be posted on the web page as much as possible. But some material may only be put on the Moodle (for copyright reasons).Slide20
Voluntary additional literature:Philip Armitage “Astrophysics of Planet Formation” (Cambridge University Press)Lecture notes on which this book was based:
http://arxiv.org/abs/astro-ph/0701485v1
The review
‘bibles’ of star and planet formation:Protostars and Planets IVProtostars and Planets V
Protostars and Planets VI. Book is not yet out. Conference was in Heidelberg, July 2013. You can view the talks as movies:
http://www.mpia-hd.mpg.de/homes/ppvi/talks/Slide21
Other lecture material of interest:„Physics of accretion disks and planet formation“ by Christoph Mordasini (MPIA Heidelberg) http://www.mpia-hd.mpg.de/homes/mordasini/lectureWS1112.html„Planetenentstehung“ by Willy Kley (University of Tübingen)
http://www.tat.physik.uni-tuebingen.de/~kley/lehre/planeten/index.htmlSlide22
Thanks to ...... for materialChristoph MordasiniCarsten Dominik
Willy Kley
The field of planet formation is quite an expansive field. I have received lots of very valuable information and material from the following people, to whom I am indebted:Slide23
Advertisement:Lecture „Astrobiologie und Astrobiophysik II“by Lisa KalteneggerStart: second week of this semester (next week)Wednesdays, 17:15-18:45INF 227, HS 2Will cover lots of stuff about exoplanets!
Will be in GermanLevel = Bachelor