Observational Properties
of Protoplanetary Disks
Leonardo Testi - ESO/Arcetri
[email protected]; [email protected]
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Today:
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Tracing water, deuteration and link with Solar System
Complex Organic Molecule
Transition disks
Questions from this morning
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CO Snowlines: why are so hard to see?
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Close to the star and traced by *faint* molecules!
Need ALMA sensitivity!
We can observe directly only gas-phase molecules
How can we probe the cold midplane gas?
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Need molecules that do not condense on the grains (hard/faint)
Moderate desorption due to CR&induced UV possible
Part X
Water and Complex
Molecules
(van Dishoeck+2014)
The complex chemistry of YSOs and disks
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Tracing water in protostars
and disks
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Systematic difference
between HD, HDO
and other molecules
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Need resolved
measurements
(Ceccarelli+2014)
(Ceccarelli+2014)
Deuteration
(Cleeves+2014)
Models of Deuteration in Disks
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Disk is not capable to produce the deuteration => ices
Can we detect water with ALMA in disks?
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(Brinch et al. 2010)
è Herschel
(Hogerheijde et al. 2011)
detects much less water than originally
expected in protoplanetary disks
è Freeze out and dust settling expose only a tiny
fraction of the water ice to stellar radiation
è Deuterium fractionation and water isotopes
accessible
(van Dishoeck 2013)
Chemical complexity
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Complex molecules are formed on the ices and then can be
released in the gas phase as ices sublimate
Chemical complexity
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Climbing the ladder of chemical complexity
(Sanchez-Monge+2014)
Hot molecular cores
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This process is commonly observed in hot molecular cores
where young massive stars evaporate the icy mantles
(Jorgensen+2012)
Chemical complexity
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Simple sugar (glycolaldehyde) in low mass protostar
(van der Marel+2014)
(Belloche+2014)
Chemical complexity - Future
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H2CO
Full ALMA sensitivity required
(Jimenez-Serra+2014)
Very hard to detect complex molecules in disks
5 min pause
• How can we explain the radial distribution of [D]/
[H] in our own Solar System?
• Are we focusing too much on a chemistry of life
tuned on what we have on Earth?
• What about chirality?
Take home points
• Molecular spectroscopy is potentially a very powerful tool
to study disk kinematics, physics and chemistry
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Complex modelling
Missing/uncertain key data: collision rates, reaction rates
• ALMA will be the prime tool to study gas in disks
• kinematics, physics and chemistry of disks
• The Chemical heritage of the Solar System may be linked to
a pre-disk evolution
Part XI
Transitional Disks
and Disk Dissipation
What if we carve a hole?
νFν
ν(4q-2)/q
ν3+β
νFν
λ
λ
Transition disks
Williams&Cieza2011
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~10-20% of disk population, likely represent a variety of
evolutionary patterns
Transition disks
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Lack of dust opacity in the inner disk
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Grain growth?
Photoevaporated hole
Dynamically carved hole
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Fast!
Early growth in protostars
Evolution???
(Pinilla et al. 2014)
Grain properties in TDs
(Armitage)
Disk photoevaporation
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Energetic stellar radiation heats the disk surface
Unbound material flows away from the system
EUV+FUV+X-rays
(Gorti+2009)
Simple Theory of Photoevaporation from in
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Outer disk inflow maintains inner disk, when Macc fades a gap is created
and the inner disk is removed
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Fast removal of inner disk
Monday, 7 May 2012
Evidence of photoevaporation
EUV – M ~ 10-10M⊙
(Pascucci+2011)
X-ray – M ~ 10-8M⊙ /
Ercolano & Owen 2010
• Blueshifted [NeII] line from the wind
Monday, 7 May 2012
(Alexander+2014)
Scenario
(Andrews+2011)
Dust depleted inner regions
• mm continuum images reveal inner cavity
(Rosotti+2013)
Accretion in TDs
• Accretion phase should be very short
(Manara+2014)
Accretion in TDs
• There is a relatively large population of TDs with large inner
holes that show accretion compatible with classical disks
(Perez+2015)
ALMA results on TDs
(Perez+2014)
(Fukagawa+2013)
ALMA results on TDs
• Vortices or planet-induced azimuthal asymmetries in the gas
distribution that lead to particle confinement
Take home points
• Photoevaporation alone has troubles in explaining
transition disks
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Especially the accreting disks with large inner holes
• A combination of various effects may conspire to explain
the characteristics of transition disks
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Combination of planet formation and photoevaporation?
• ALMA reveals asymmetries in the large grains distribution
in the outer disk
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may promote formation of large bodies in the outer disk