Star and Planet formation -...
Transcript of Star and Planet formation -...
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Star and Planet formation
Carsten DominikUniversity of Amsterdam, 2011
Main Books:
• Main Books– S.W. Stahler & F. Palla, “The formation of stars”– P. Armitage: “Astrophysics of Planet Formation”
• Additional Books– L. Hartmann, “Accretion processes in star
formation”– I. Pater & J. Lissauer: Planetary Physics– Protostars and Planets II, III, IV, (V)
• Thanks– Kees Dullemond, Ewine van Dishoek, Rens
Waters, Inga Kamp, and many others.
Syllabus
We use the Syllabus Inga Kamp and MarcoSpaans have written. I am modifying andupdating it throughout the course
• online www.astro.rug.nl/~kamp - Lectures• Updated version and new chapters
– www.astro.uva.nl/~dominik/Teaching/SPF
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Projects• Numerical integration of Bonner Ebert sphere• BPCA cluster formation• Numerical study of Disk stirring• Numerical study dust growth by settling and radial
drift.• Review paper summaries (30 min talk)‒ Nice model as constraint for solar system (Gomez et al2004)
‒ Irregular moons of major planets (Jewitt &Haghighipour 2007)
‒ Exoplanet statistics overview (Udry & Santos 2007)– Short-lived radio nuclides and relative timing of SS formation
(Dauphas & Chaussidon 2011)
Course outline I
1. Overview and Introduction, Properties ofstars and the solar system (what are wetrying to understand?). Start with MolecularCloud properties
2. Molecular clouds, core, observationalproperties. Molecules as tracers ofproperties and evolution.
3. Cloud cores, stability and collapse4. Pre-main-sequence stars5. High mass star formation: Clusters
Course outline II
6. Circumstellar disks: Viscous accretion7. Circumstellar disks: Irradiation8. Dust motion and aggregation in disks9. Planetesimals and further growth to terrestrial
planets10. Giant planet formation: Gravitational instability
versus core-accretion11. Chemical evolution from molecular clouds to
planets12. Comets, asteroids and debris disks13. Extrasolar planets, Planet Migration and further
puzzles.
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The geocentric model
Before 16th century• the geocentric model
was everywhere• Aristarchos of
Samos (280BC) hadsuggested aheliocentric model
• Even Tycho Braherejected it becauseof not parallaxesobserved (<=0.77”for Proxima Cen)
The heliocentric model
Nicolaus Copernicus (1473 - 1543)
The heliocentric model
Johannes Kepler (1571 - 1630)
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Keplers laws
1. The planets revolve onelliptical orbits, and theSun is located in onefocal point
2. The area swept out bythe radius vector fromthe Sun to the planet perunit time is constant
3. The square of the orbitalperiod T divided by thecube of the semi majoraxis a (= mean distance)is the same for allplanets
!
dAdt
=12r2 d"dt
#
$ %
&
' (
!
T 2
a3=
4"G M# +mpl( )
The planets
zon
Diameter Earth = 12.756 km
Size to scale
Mer
cury
Venu
sEa
rthM
ars
Jupi
ter
Satu
rn
Uran
us
Nept
une
Plut
o
1,00,4 0,9 0,5 11 9 4 4 0,2
1101781
1846
The planets
zon
Units = 150.000.000 km = 1 AU
Distance to scale
Mer
cury
Venu
sEa
rthM
ars
Jupi
ter
Satu
rn
Uran
us
Nept
une
Plut
o
1,0
0,4
0,71,5
5,2 20 30 409,6
asteroïden
}
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Kinds of planets
zone 1
zone 2
zone 3
Zone 1: earth-like
Zone 2: Gasgiants
Zone 3: icy bodies
asteroïden
Earth-like planets
Properties: • Silicates• rather small (4.000 - 13.000 km Ø)• High densities (3 - 5,5 gram/cm-3)
0,4 0,9 1,0 0,5
The Gas giants
Properties: • Lots of gas and ice• rather large (50.000 - 140.000 km Ø)• low densities (0,6 - 1,6 gram/cm-3)
11 4,0 3,99,2
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Orbits
40 AE
Pluto
NeptuneUranus
Saturn
Jupiter
Asteroids
Mars
Directi
on o
f rot
ation
Orbits in one plane
40 AE
PlutoNeptunus
Uranus
Saturnus
Jupiter
Mars
Direction of rotation
Radioactive dating, Isotopes• Meteorites:4.55 x 109 yr• Chondrules:4.56 x 109 yr• Rocks on Earth: 4.3 x 109 yr• Rocks on Moon: 4.4 x 109 yr• ! Sun and planets formed at
the same time (within few x106 yr inside a few AU)
• D/H ratios in the SS:!Planets formed frominterstellar matter (D is rapidlydestroyedinside stars)
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Isotopes
• D/H ratios in the SS:!Planets formed frominterstellar matter (D is rapidlydestroyedinside stars)
• Oxygen isotopes:! Severalsources of oxygen have beenmixed in the Solar System,e.g. Gas, ice, and solid forms
Dynamical constrains: small bodies
• Before Jupiter (green) and Saturn (yellow) reach their 2:1resonance
• Scattering of planetesimals into inner Solar System whenresonance occurs
• After ejection of planetesimals (Uranus: cyan, Neptunus: blue)Dynamics of small bodies carries imprint of early SS dynamics
The Nice model (Gomez et al 2005)
Main properties of the solar system I• Orbits of major planets are almost circular, almost co-
planar, almost in the equatorial plane of the Sun.• Orbits of major planets are confined to <30AU. They
don’t cross, don’t even come close• Little debris except asteroid Belt, Jupiters Trojans,
Kuiper Belt. Regions between planets are unstable.• 1012 comets in Oort clouds.• Rotation of 6 planets along with orbital motion, but
Venus, Uranus and Pluto rotate retrograde.• Most planets have natural satellite systems, on low
inclination, low eccentricity orbits. Distant smallmoons can have all kinds of orbits.
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Main properties of the solar system II• Planetary masses account for less than 0.2% of the
solar system, dominated by far by Jupiter and Saturn.Asteroids and KB Comets are minor contributions tomass.
• The planets carry 98% of the angular momentum inthe system.
• Rocky planets close to the Sun, Gas planets between5 and 10AU, ice planets (including Uranus andNeptune) further out.
• Ages 4.56Gyr for the oldest rocks. Differentiatedrocks at 4.4-4.56Gyr, Lunar surface 3.1-4.4Gyr.
• Isotopically well mixed, even though elementabundance vary greatly throughout the system.
• Cratering record talks about much higher impactrates before 3.8Gyrs ago.
Exoplanets
Origin of Life
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A brief history...
• 1755: Kant postulates that solar system formed from‘Urnebel’ (‘solar nebula’)
• 18th-19th: Observations of dark clouds• 1904: Hartmann: Discovery of interstellar gas• 1930: Trumpler: Discovery of interstellar dust• 1944: von Weizsäcker forwards idea that planets formed in
vortices in a turbulent protoplanetary disk (=solar nebula)• 1952: Lüst develops first real theory of pp accretion disk• 1960-70’s: Mapping of interstellar clouds (HI 60’s, CO: 70’s)• 1961: Hayashi: first theory of pre-main sequence evolution• 1969: Safronov published theories of accumulation of solid
particles and planet formation (most of his theories are stillhighly relevant today!)
• 1977: Shu: first theory of cloud collapse
A brief history...
• 1980’s: IRAS satellite maps at 12, 25, 60 and 100 µm:discovery of many young stellar objects (YSOs).
• 1984/1987: Lada & Wilking, Adams, Shu & Lada: YSOclassification and evolutionary sequence (class I, II, III).
• 1984: Auman et al., Smith & Terrile: discovery of disksaround mature main-sequence A stars (Vega, "-Pic).
• Late 80s/early 90s: Infrared and sub-mm observatories:indirect evidence of disks.
• Mid 90s: Hubble images of disks: direct evidence for disks• 1995/1996: Mayor & Queloz (1995), Marcy & Butler (1996):
discovery of extrasolar planets around solar type stars• >1995: Explosion of research on disks and extrasolar
planets.
Historical theories
1.II Models of Solar System Formation
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Historical theories
1.II Models of Solar System Formation
Historical theories
1.II Models of Solar System Formation
Kant 1724-1804
Laplace 1749-1827
Overview: The egg nebula
EagleNebula(M16)
Picture credit: T.A. Rector & B.A. Wolpa
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Detail of Eagle Nebula: HST
Chameleon molecularcloud:
example of low mass starforming region
No star formation in Barnard 68
Optical multi-colourOptical multi-colourimageimage
Optical-IR multi-colourOptical-IR multi-colourimageimage
((Alves Alves et al.)et al.)
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‘Isolated’ Star Formation
M.Hogerheijde1998, after Shu et al. 1987
Planets form in the disk (?)
Artist’s impression of planet formation...
Grinding asteriods back to dust...