millimeter-wavelength observations of circumstellar disks and what they can tell us about planets a....
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Millimeter-Wavelength Observations of Circumstellar
Disks
and what they can tell us about planets
A. Meredith HughesMiller Fellow, UC Berkeley
David Wilner, Sean Andrews, Charlie Qi, Catherine Espaillat, Jonathan Williams, Nuria Calvet, Paola D’Alessio, Antonio Hales, Simon Casassus, Michael Meyer, John Carpenter, Michiel Hogerheijde
Star and Planet Formation Overview
cloud grav. collapseprotostar+ disk
+ envelope + outflow
PMS star+ disk
MS star+ debris disk+ planets?
Adapted from Shu et al. 1987
Circumstellar Disk Evolution
Protoplanetary
Pre-MS stars
Gas-rich
Primordial dust
Debris_____
Main sequence
No (or very little) gas
Dust must be replenished
planets?
Some Questions:What physical processes shape each stage?
What physical processes drive dispersal?When and how do planets form?
What are the properties of the planets?
AU Mic, Liu et al. 2004HH 30, Burrows et al. 1996
F
Circumstellar Disk Structure
star disk
Why Millimeter Interferometry?
• Optically thin dust emission• Molecular line emission• High spatial resolution
HD 163296, Grady et al. (2000)
Adapted from Dullemond et al. (2007)
• Low star/disk contrast
2. Resolving Debris Disk Structure
The Bird’s-Eye View1. Disk Dissipation
Constraining physical mechanism(s) driving dissipation• Imaging Inner Holes
• Molecular Gas Content
How debris disks can tell us about planets•Finding Uranus/Neptune analogues
•Edge-on debris•Masses of directly-imaged planets
What I’m NOT going to talk about
0. Protoplanetary Disks as Accretion Disks
Observable signatures of viscous transport processes:•Magnetic fields (polarization)
•Turbulence (HiRes spectroscopy)• Large-scale structure
(But you should ask me about it if you’re interested!)
1. Disk Dissipation
Identifying Transition Disks: SED Modeling
log
log
F
star
dust
log lo
g
F
dust
starmid-IR deficit
“Normal” star + disk SED Transitional SED
€
T ∝ r−1/ 2
Equilibrium
temperature:
€
peak ∝T−1+Wien Law:
€
∝ r1/ 2
10x less CO than expected
Also true for other transition disks in literature (GM Aur, TW
Hya)
Modeling Transition Disks in CrA
Inner holes everywhere?~10% of low- and intermediate-mass stars have transitional SEDs (e.g. Muzerolle, Cieza, Uzpen et al.)
Why the “?”
Boss & Yorke 1996
“…we remain skeptical of the existence of such a large central gap devoid of dust”
-- Chiang & Goldreich (1999)
Hughes et al. (2010)
Stellar photosphereInner diskWall
Outer disk
Calvet et al. (2002)
TW Hya GM Aur
Calvet et al. (2002)
Zooming in on the mid-IR…
Calvet et al. (2005)•Spectral type K7 (Rucinski & Krautter 1983)
•Age ~10 Myr (Webb et al. 1999)
•Distance 51 pc (Mamajek 2005)
•Spectral type K5 •Age ~1-5 Myr (Gullbring+ 1998)
•Distance 140 pc (Bertout & Genova 2006)
Weinberger et al. (2002) Schneider et al. (2003)
Predicted inner hole size: 4 AU
Predicted inner hole size: 24 AU
Testing the paradigm: SED deficit = inner hole
€
(F ∝κΣ)
TW Hya GM Aur
Calvet et al. (2002) Calvet et al. (2005)
Observations
Hughes et al. (2007) Hughes et al. (2009b)
Observations
Courtesy J. Williams (PIs Andrews, Brown, Cieza, Hughes, Isella, Mathews, Pietu)
Origin of the inner hole?
Similar for TW Hya
Accretion: Taurus median
Gullbring et al. 1998
No cold CODutrey et al. 2008
Hot CO at 0.5 AU
Salyk et al. 2007
Small amt of hot dustCalvet et al. 2005
Cavity is not empty!
Dullemond & Dominik (2005)
Ireland & Kraus (2008)
in disk center - Dynamical mass + photometry
- Keck AO imaging (<40 Mjup) - Hot CO, accretion
rate
Alexander, Clarke & Pringle (2006)
Chiang & Murray-Clay (2007)
Origin of the inner hole?Theory: Consistent Inconsistent
- in disk center - Lack of cold CO
- Sharp transition b/w
inner/outer disk
- in disk center - Massive outer disk
- High accretion rate- in disk center - m-size grains in- Massive outer disk inner disk - Lack of cold CO - Origin of gap?- High accretion rate
- Accretion rate - Mass/distance?- Small grains in inner disk-Sharp inner/outer disk transition
4) Binaritye.g. Ireland & Kraus (2008)
5) Planet-Disk Interactione.g. Lin & Papaloizou (1986), Bryden et al (1999), Varniere et al. (2006), Lubow & D’Angelo (2006)
3) Inside-out MRI ClearingChiang & Murray-Clay (2007)
2) Photoevaporatione.g. Clarke et al. 2001, Alexander & Armitage (2007)
1) Grain Growth ()e.g. Strom et al. (1989), Dullemond & Dominik (2005)
Bryden et al (1999)
The Plane
€
˙ M − Mdisk
Najita et al. (2007)
Alexander et al. (2007)
courtesy S. Andrews
photoevaporationbinaries
planets grain growth
Andrews et al. (2010)
What’s next?
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QuickTime™ and aTIFF (Uncompressed) decompressor
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What will ALMA do?
1. Solve all of science
2. Sensitivity:• Finding transition disks• Statistics - planet populations• Molecular gas evolution
3. Resolution:• Measuring accurate cavity sizes• Gaps
4. Sensitivity + Resolution:• Planetary accretion luminosity• Gas in the cavity
log
log
F
duststar
“Pre-Transitional” SED
Wolf & D’Angelo (2005)
2. Resolving Debris Disk Structure
Debris DisksFomalhautKalas et al. (2005)
Weinberger et al. (1999)
PicFitzgerald et al. (2007)
HR 4796ASchneider et al. (1999)
Debris DisksIf debris disks were primordial, they wouldn’t be there
dust ≤10 Myr
Debris disks look different at different wavelengths
70 m; Su et al. (2005) 350 m; Marsh et al. (2006) 850 m; Holland et al. (2006)
At least 15% of nearby main-sequence stars have debris disks(Habing et al. 2001, Rieke et al. 2005, Trilling et al. 2008, Hillenbrand et al. 2008)
How Debris Disks Tell Us about Planets
1. Access to otherwise unobservable Uranus/Neptune analoguesQuickTime™ and aTIFF (Uncompressed) decompressor
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QuickTime™ and aCinepak decompressor
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Courtesy M. Wyatt
Wilner et al. (2002)
How Debris Disks Tell Us about Planets
1. Access to otherwise unobservable Uranus/Neptune analoguesQuickTime™ and aTIFF (Uncompressed) decompressor
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Hughes et al. (in prep)
Corder et al. (2009)CARMA 230 GHz
HD 107146
How Debris Disks Tell Us about Planets
2. Vertical structure of edge-on debris disksQuickTime™ and aTIFF (Uncompressed) decompressor
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From Thebault et al. (2009)
Wilner et al. (in prep)
How Debris Disks Tell Us about Planets
3. Constraints on the masses of directly-imaged planets
Chia
ng e
t al. (2
009)
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Kalas et al. (2008)
How Debris Disks Tell Us about Planets
3. Constraints on the masses of directly-imaged planets
Hughes et al. (in prep)
QuickTime™ and aTIFF (Uncompressed) decompressor
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What’s next?
QuickTime™ and aTIFF (Uncompressed) decompressor
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QuickTime™ and aTIFF (Uncompressed) decompressor
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What will ALMA do?
• (Some) debris disks will be roughly as easy to image as protoplanetary disks are now• Statistics - planet populations• Excellent linear resolution• (Molecular gas?)
Summary
IR Deficit mm flux cavity
1. Disk Dissipation
Calvet et al. (2005)
Most transition disks probably cleared by
planetsBryden et al (1999)
2. Resolving Debris Disk Structure
Access to otherwise unobservable Uranus
analogues
Edge-on systems
Constraining planet massesMolecular gas?
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