Willy Benz (Bern)Willi Kley (Tuebingen)Sascha Krivov (Jena)Sebastian Wolf (Kiel)

Hans Zinnecker (Potsdam)

Michael R. Meyer, Institute for AstronomyETH-Zurich

The (Un)Lonely Planet Guide:Formation and Evolution of Planetary SystemsWorking Group ReportPathways to Habitable Planets15 September, 2009

Different Flavors of Planet Formation

Typical Disk ParametersParameter Median ~1σ Range

Lg(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 Myr

Temperature 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 AU

R(outer) 200 AU ~90-480 AU

Surface density power [Σ(r) ~ r-p] [Hayashi min. mass solar 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

Initial Conditions in Protostellar Disks.

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

Planetesimal Formation Timescales:

» tp ~ p x Rp / [ d x d]

– d ~ M*/a and d~ sqrt(M*/a3)

– following Goldreich et al. (2004); Kenyon & Bromley (2006).– Normalize: @ 3 Myr - [3 Mearth, 5 AU, 1 Msun]

» tp ~ [p 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).]

Draining of Solids

• Gas drag migration of meter-sized bodies (1 AU in 100 yrs).

• Type I migration of Lunar mass bodies (1 AU in < 105 yrs).

• Solar System lost <= 50 % of available solids.

• Constraints on differential abundances in young clusters.

Evidence for Type II Migration

in Multiple Planets

Giant Planet Formation -- While core accretion is favored, GI happens.

R. Rafikov (2009) A. Boley (2009)

How does chemistry affect planet formation?Search for discontinuities in gas phase abundances

Gail (2002); Garaud & Lin (2007); Ciesla (2009); 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)

=> Primordial disks last longer around lower mass stars.

=> Duration of the “transition”

~105 yrs.

Carpenter et al. (submitted)

Disk Evolution in Upper Sco at 5 Myr: 220 Stars

Primordial (Gas Rich) Disks: » Required for gas giant planet formation.

Debris (Dusty) Disks:» Trace evolution of planetesimal swarms.

How can you tell the difference?» Absence of gas (Gas/Dust < 0.1).

» Dust processing through mineralogy (silica?).

Debris dust may be generated early on in gas rich disks and could dominate opacity before gas dissipates!

Herschel will be powerful probe of the final stages of gas dissipation (ice giant formation).

Gorti & Hollenbach (2008); GASPS and DIGIT Open Time Key Programs

Don’t forget about ice giant formation!

Neptune and Uranus…one is hot, the other not!

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

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Earth-Moon collision released 5 x10-3 Mearth in hot gas.

If condensed to micron sized dust, more than 100x above detection limits.

Lifetime of such dust ~ 103 years over timescale of 107 yrs.

Such collisions are rare in Spitzer samples.

Lisse et al. (2009)

…you can see them with nextgeneration instruments!

Miller-Ricci, Meyer, Seager, Elkins-Tanton(2009)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Planetesimal Dynamics = Compositional Differences

Raymond et al. (2004; 2006); Bond et al. (submitted)

Time

Du

st P

rodu

ctio

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Planets

No Planets

The connection between planetesimal belts and presence/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), Kospal et al. (2009), Bryden et al. (2006)Notable Exceptions: HD 69830, HR 8799, Fomalhaut, Beta Pic, eps Eri…

Spitzer/FEPS (Meyer et al. 2006)The Last Word: Carpenter et al. (2009)

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

Inner Hole Sizes and Multi-temp components: cf. Morales et al. (2009)

Constraining Exozodiacal Dust Background

Circumstellar Disk Report - Exoplanet Forum (Hinz, Bryden et al. 2008)See also talk by O. Absil and 1-2 meter visible space coronagraph concepts.

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

Spitzer @ MIPS-24 JWST-MIRI Herschel

Embar

go

unt

il af

ter la

unch

Population Synthesis Models:Terrestrial planets may be very common!

Ida & Lin (2004) Mordasini et al. (2009)

The (Un)Lonely Planet Guide:

Disk properties exhibit dispersion and are function of star mass.

Draining of solids/migration of volatiles present danger/opportunity.

While core accretion is favored, GI happens.

Data are consistent with terrestrial planets being very common.

Q: Does planet formation favor dynamically dense systems?

Q: Is planet formation in multiples/rich clusters different?

Google Maps: Get Directions for ‘Habitable Planets’ (text only)Compelling arguments for PROBES NOW.

Develop strong exoplanet science cases for a VARIETY of

instrumentation for ELTs.

Invest now in DIVERSE technologies for flagship mission in

order to SAVE MONEY when final design concept needed.

The result must teach us something FUNDAMENTAL about

the formation and evolution of planetary systems.