The formation of stars and planets
Lecture by C.P. Dullemond
Max-Planck-Institute for Astronomy Heidelberg
Sorry about:
• Topic of Star- and Planet Formation is too vast to
cover completely, and in sufficient depth, in 15 hours.
• We will have to gloss over many things...
• Many important topics not included, for example:
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Origin of ‘metal’-enriched matter from which we are built
Star formation on galactic scale (e.g. star-burst galaxies)
Chemistry of star formation, photodissociation of molecules
Pre-main sequence stellar evolution
High-mass star formation (unless voluntary extension!)
Literature:
• S.W. Stahler & F. Palla, “The formation of stars”
• L. Hartmann, “Accretion processes in star
formation”
• The review ‘bibles’ of star and planet formation:
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Protostars and Planets II
Protostars and Planets III
Protostars and Planets IV
(next year) Protostars and Planets V
Thanks to ...... for material
The field of star and planet formation is quite a large field. I
have received lots of very valuable information and material
from the following people, to whom I am indebted:
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•
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•
•
•
•
Ewine van Dishoeck
Carsten Dominik
Christian Fendt
Anders Johansen
Klaus Pontoppidan
Frithjof Brauer
Sascha Quantz
• *Many others*
Technical notes on the lecture:
• Target group:
– PhD students and advanced undergraduate students
– Physics and astrophysics
• Goals:
– Half overview, half in depth
– Mostly theory, but strong link to observations
• Powerpoint material will be put on my web site:
– www.mpia.de/homes/dullemon/lectures/starplanet/
Technical notes on the lecture:
• Style of lecture :
– Working out simple analytical models (of cloud cores, of
disks, of particle motion, particle agglomeration etc.)
– Discussion of state-of-the-art models with physical
explanation.
– Comparison of models with observations
• We need solid basis in the physics of astrophysics
(hour 2+3)
• But first a quick overview... in pictures and movies
The formation of stars and planets
Day 1, Topic 1:
Introduction
and
Overview
Lecture by: C.P. Dullemond
Birthplace of stars: Molecular Clouds
Ophiuchus Giant Molecular Cloud (by Loke Tan)
Birthplace of stars: Molecular Clouds
Ophiuchus Giant Molecular Cloud (by Loke Tan)
Forming stars from Molecular Clouds
M. Bate
Exeter
UK
Zur Anzeige wird der QuickTime™
Dekompressor „Cinepak“
benötigt.
Very dense
Molecular
Cloud: very
aggressive
star formation
‘Isolated’ Star Formation
M.Hogerheijde1998, after Shu et al. 1987
In the beginning...
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
Feeding the infant star...
McNeal’s
Nebula
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Infall of matter onto protostar is energetic: lots of radiation
In above image some radiation escapes via cavity.
Most of radiation escapes at long wavelength (infrared), because
cloud is transparent at those wavelength.
Far-IR wavelength telescopes have low resolution so far, so what’s
really happening down there is still difficult to study.
Not all ‘food’ is welcome: outflows...
Not all ‘food’ is welcome: outflows...
A zoom-in to a massive star forming region
Zoom-in
M16
(Eagle)
M17
(Horseshoe)
Milky Way
M8
(Lagoon)
Hale-Bopp
Jupiter
Picture credit: W. Keel
A zoom-in to a massive star forming region
Eagle
Nebula
(M16)
Picture credit: T.A. Rector & B.A. Wolpa
A zoom-in to a massive star forming region
Eagle
Nebula
(M16)
Picture Credit: J. Hester & P. Scowen
A zoom-in to a massive star forming region
Eagle
Nebula
(M16)
Picture Credit: J. Hester & P. Scowen
A zoom-in to a massive star forming region
size of our solar system
Eagle
Nebula
(M16)
Picture Credit: J. Hester & P. Scowen
Clearing of the remnant birth cloud
A star+disk appears...
A star+disk appears...
HST image of AB Aurigae by Carol Grady
Planets form in the disk (?)
Artist’s impression of planet formation...
Grinding asteriods back to dust...
Grinding asteriods back to dust...
Planets and asteroids have formed, some asteroids get destroyed and
produce the dust you observe in the image. Can the dust trace the
location of (invisible) planets?
The early life of a
newly formed star
Zero-age main sequence (ZAMS)
O
B
Oh, Be A
Fine Girl,
Kiss Me
(Right
Now
Sweety!)
A
F
G
star
mass
K
M
The Harvard
classification.
Annie Jump
Cannon,
Henry Draper
Pre-main-sequence: the infancy of a star
Palla & Stahler
Pre-main-sequence: the infancy of a star
• Protostar = self-gravitating hot ball of gas,
continuously being fed by accreting matter
• At first: no internal nuclear heat production
• Star cools by radiation:
– Kelvin-Helmholz time scale
• Star contracts, central density and temperature
increases (!)
• Deuterium ignites as soon as Tc >= 1x106 K
– Thermostat: ds/dTc<0, i.e. too hot: star swells, Tc goes
down, and deuterium burning slows
• Star becomes fully convective
• Stellar radius inflates: can reach 3...5 R.
Pre-main-sequence: the infancy of a star
• (We are now in the T-Tauri star phase)
• Star contracts slowly
– with constant temperature for low mass stars, i.e. they
move vertically downward in the HR diagram
• Tc and c increase until:
• Hydrogen ignition
– Prolonged hydrogen burning starts
– This is the start of the ‘adult’ life of the star
– Star reached the ZAMS
Age and mass determination of PMS stars
Testi et al.
Martin et al.
Overview of the lecture
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Day 1:
– Introduction
– Radiation physics
– Hydrodynamics and Magnetohydrodynamics
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Day 2:
– Giant Molecular Clouds
– Self-gravitating hydrostatic spheres
– Collapsing clouds
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Day 3:
– Viscous evolution of protoplanetary disks 1+2
– Irradiated protoplanetary disks, SEDs, observations
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Day 4:
– Magnetospheric accretion, jets, outflows
– Motion of particles in disks
– Agglomeration of particles in disks
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Day 5:
– The solar system and extrasolar planets
– Formation of planets
– Migration of planets and outlook