Planet Forming Disks:A Function of Stellar Properties

Michael R. Meyer, Institute for Astronomy, ETH-ZurichFrom Disks to Planets: Learning from Starlight - 2009 EARA Workshop

Different Flavors of Planet Formation

Are planetary systems like our own are common orrare among sun-like stars in the Milky Way galaxy?

Q: What are the initial conditions of planet formation?

Q: What is the time available to form gas giant planets?

Q: What is the history of planetesimal collisions vs. radius?

Q: How do the above vary with stellar properties?

Because the answers are subtle,need large samples over a wide range of ages.

From Active Accretion to Planetary Debris Disks...Images courtesy of M. McCaughrean, C.R. O`Dell, NASA, and P. Kalas.For recent review see Meyer et al. (2007) Protostars & Planets V

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Gas-rich disk ~ 1 Myr old

Planetary debris disk ~ 100 Myr old

Solar system debris disk 4.56 Gyr old!

Star with magnetosphericaccretion columns

Accretion disk

Disk drivenbipolar outflow

Infallingenvelope

Different Wavelengths Trace Different Radii!

NIR MID FIR sub-mm

0.1 1.0 10.0 100 AU

1

Optically-thick/geometrically thin

L*r

angle θ

Power/area absorbed ~ L*4πr2 Sin θ

Δ

L*4πr 2

Δr

~ L* r 3

~

Power/area emitted = σT4 L* r 3

~

(r >> Δ)

T(r) ~ r -3/4

Also true for accretion energy.

flat, black disk

Lynden-Bell & Pringle 1974, MNRAS, 168, 603. Adams, Lada, & Shu 1988, Ap. J., 326, 865.

Star Luminosity, L*

1

Radiative heating: isolated particle

Luminosity L

Particle radius a (spherical; rapidly spinning)Temperature T

Distance r

Absorbed radiative power: πa 2 x L4πr 2

Emitted radiative power: 4πa 2 x σT 4

T = ( )1/4 r -1/2

L16πσ

Using εν for small particles: T ~ r -2/5

cf L. Spitzer, Jr., Physical Processes in the Interstellar Medium, ch. 9.1

Blackbody Disk with Dynamically Cleared Gap

NIR MID FIR sub-mm

0.1 1.0 10.0 100 AU

SEDs of T Tauri Stars in ChamaeleonRobberto et al. (2003).

SEDs of T Tauri Stars: AConsequence of Inner Holes?

Chiang & Goldreich 1997;Dullemond et al. 2001;

see also Calvet et al. 2003

What disk properties do we care about?*

Total disk mass: Mdisk, Mdisk/M*

Outer & inner radii: Rout, Rin

Surface density profile: Σ(r) = Σo r-p

Dust grain size distribution: n(a) ~ no a-q ; amin, amax

Dust grain opacity law: κν ~ νβ

Optical depth: τν = κν Σ(r)Temperature profile: T(r) ~ To r-q

Scale height, Midplane density: H(r), ρo(r)Viscosity: νv = α cs H ~ νvo rγ (MRI?)Composition (gas, dust), Ionization, asymmetries, etc. * <MEAN> and σ as f(star, environment, time)…

Stellar Properties Influencing Disk Evolution

• Mass:

• Luminosity & Incident Spectra:

• Angular Momentum:

• Composition:

• Companions versus Mass and Orbital Radius:

• Formation environment:

Confounding Variables:T Tauri Disk Evolution and Errors in Age

Transition Disks:Espaillat et al. (2007);Brown et al. (2007)Few disk parameters correlate:Bouwman et al. (2008)Pascucci et al. (2008)Cortes et al. (2008)Watson et al. (2007)

How does chemistry affect planet formation?

Gail (2002); Cody & Sasselov (2005); Garaud & Lin (2007); Bond et al. (in prep)Image courtesy N. Gehrels (PSU)

Gas disk chemistry may vary with stellar mass…

Pascucci et al. (2009); cf. Carr & Najita (2008); Pontoppidan et al. (2008)

Typical Disk ParametersParameter Median ~1σ Range

Log(M(disk)/M(star))[all ~1 Myr] [detected disks only]

-3.0 dex-2.3 dex

±1.3 dex±0.5 dex

Disk lifetime 2-3 Myr 1-6 MyrTemperature power law [T(r)~r-q] 0.6 0.4-0.7

Taken from (or interpolated/extrapolated from):Muzerolle et al. (2003), Andrews & Williams (2007), Hernandez et al. (2008), Isella et al. (2009)

Parameter Median ~1σ Range

R(inner) 0.1 AU ~0.08-0.4 AUR(outer) 200 AU ~90-480 AUSurface density power [Σ(r) ~ r-p][Hayashi min. mass nebula][steady state viscous α disk]

0.61.51.0

0.2-1.0(predicted)(predicted)

Surface density norm. Σo (5AU) 14 g cm-2 ±1 dex

Differences in Disk Temperature Profiles:

Garaud & Lin (2007) compared to Hersant et al. (2001)

NICMOS/HST Mosaic F810W/F110W/F150W of NGC 2024 (Liu, Meyer, Cotera, and Young 2003, AJ)

Color_1

Col

or_2

★

★ ★Star+Dust Star+

Dust+Disk

Star

★Star+Disk

Does the observedrange in initial diskmass (e.g. Andrews &Williams, 2005)explain the observedrange in disklifetimes?

Haisch et al. 2001;Hillenbrand et al. (2002);Muzerolle et al. (2003).

CA

I For

mat

ion? Te

rres

tria

l Pla

nets

?

Chr

ondr

ules

?

Inner (< 0.1 AU) Accretion Disk Evolution 0.1-10 Myr

CA

I For

mat

ion? Te

rres

tria

l Pla

nets

?

Chr

ondr

ules

?

Inner Disk Lifetime

Freq

uenc

y

< t > ~ 3 Myr

Inner (< 0.1 AU) Accretion Disk Evolution 0.1-10 Myr

Haisch et al. 2001;Hillenbrand et al. (2002);Muzerolle et al. (2003).

FUV and (or?) X-rays in action…

Pascucci et al. (2007); Esplainat et al. (2007); Herzeg et al. (2007)

No massive gasdisks detectedaround 35 starswith ages 3-100Myr. Less than0.1 Mjup remainsto form planets.

Hollenbach et al. 2005; Pascucci et al. 2006/7; Lahuis et al. 2007

Debris Gas? Chen et al. 2007; Roberge et al. 2006; Dent et al. 2005

Primordial Gas disk lifetimes appear to be < 10 Myr.

Rotation-Inner Disk Connection:Function of stellar mass? (Herbst et al. 2000; Currie et al.)Function of environment? (Bouvier & Clarke 2000)Not seen for debris disks (e.g. Greaves et al. in press)

Kundurthy et al. (2006); Rebull et al. (2004); Hartmann (2002))

74 stars 3-30 Myr old:

=> 5 gas-rich disks.=> no optically-thin hot dust (< 1 AU).

Silverstone et al. (2006);Cieza et al. (2007);and references therein.

Rapid Transition time thick to (very) thin inside 1 AU

Planets as a Function of Stellar Mass: What Should We Expect?

Planetesimal Formation Timescales:

» tp ~ ρp x Rp / [ σd x Ωd]

– σd ~ M*/a and Ωd~ sqrt(M*/a3)– following Goldreich et al. (2004); Kenyon & Bromley (2006).– Normalize: @ 3 Myr - [3 Mearth, 5 AU, 1 Msun]

» tp ~ [ρp x Rp x a5/2]/ [M*3/2].

– Gives Jupiter mass gas giant planet.– Massive planets farther out surrounding stars of higher mass.– Consistent with observations to date (Johnson et al. 2007).– Yet disks last longer around stars of lower mass! [Lada et al. (2006); Carpenter et al. (2006).]

0.0

0

.1

0.

2

0.

3

0.4

Siegler et al. ‘07; Currie et al. ‘07; Meyer et al. ‘08; Carpenter et al. ‘09

Evolution of Disks Around Sun-like Stars:Tracing Planet Formation? (Field & Cluster)

6.0 7.0 8.0 9.0

CAIs Vesta/Mars LHB Chondrules Earth-Moon

Planetesimals Dynamics: Water Worlds

Raymond et al. (2004; 2006); See also Kenyon and Bromley (2005)

Disk Models+Condensation+N-Body =Diverse Terrestrial Planets through Chemistry?

J. Bond (PhD Thesis, Planetary Science, University of Arizona)

From Stellar Spectra to Planetesimal Composition:

M. Jura (2006); Ashwell et al. (2005); Winnick et al. (2002); Wilden et al. (2002)

Time

Dus

t Pro

duct

ion Planets

No Planets

The connection between planetesimal belts andpresence/absence of giant planets is not clear.

No link between debris and RV planets found!Could debris disks be more common than Gas Giants?

Moro-Martin et al. (2007a; 2007b) and Bryden et al. (2006)See Beichman et al. (2005); Lovis et al. (2006); Alibert et al. (2006) regarding HD 69830.

Debris Disks vs. Metallicity:More “diverse” than RV planet systems?

Greaves et al. ‘06; Bryden et al. ‘06; Najita et al. (in preparation).

Circumstellar Disk Evolution and Multiplicity:

Complex Story T Tauri Binaries vs. Separation Debris Disks not inhibitedSimon & Prato (1995); Jensen et al. (1994) by companions.McCabe et al. (2006); White & Ghez (2001) Trilling et al. (2007)Patience et al. (2008); Pascucci et al. (2008) Wyatt et al. (2003)Ireland & Kraus et al. (2008); stay tuned…

Spitzer/FEPS (Meyer et al. 2006)The Last Word:Carpenter et al. (2008)

Evolution in Disk Luminosity: A stars: Su et al. (2006) G stars: Bryden et al. (2006) M stars: Gautier et al. (2007)

Distribution of Inner Hole Sizes

Sub-mm Observations of Debris Disks:Carpenter et al. (2005); Greaves et al. (2006; 2008); Liu et al. (2004)

Are planetary systems like our own are common orrare among sun-like stars in the Milky Way galaxy?

Primordial Disk Evolution:

- disks around lower mass stars are less massive and live longer than their more massive counterparts.

- large dispersion in evolutionary times could indicate dispersion in initial conditions.

- evolution appears to proceed from inside-out as expected.

Are planetary systems like our own are common orrare among sun-like stars in the Milky Way galaxy?

Change you can believe in!

- transition time from primordial to debris is << 1 Myr.

- planetesimal belts evolve quickly out to 3-30 AU.

- some evidence that warm debris more common in clusters?

Debris Disk Evolution:

- currently detectable systems are collision-dominated.

- more common around stars of higher mass.

- evolutionary paths are diverse.

- consistent with our solar system being common.

- connection to planetary systems unclear.

Are systems without debris those with dynamically fullplanetary systems, or those without any planets?

A Picture is Worth 1024 x 1024 Points on an SED…

A Picture is Worth 1024 x 1024 Points on an SED…

Spitzer @ MIPS-24 JWST-MIRI HerschelEm

barg

o un

til a

fter l

aunc

h

The starlight-disk connection…

Initial conditions of planet formation are set by star formation.

Star-forming environment could be critical.

Disks dissipation timescale is f(M*).

L* / T* / energetic radiation / rotation / multiplicity all play roles.

Star/disk composition/chemistry may be key.

“Hidden parameters” control disk evolution.