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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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

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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?