Download Formation & Evolution WG review - Pathways Towards Habitable

Willy Benz (Bern)
Willi Kley (Tuebingen)
Sascha Krivov (Jena)
Sebastian Wolf (Kiel)
Hans Zinnecker (Potsdam)
Michael R. Meyer,
Institute for Astronomy
ETH-Zurich
The (Un)Lonely Planet Guide:
Formation and Evolution of Planetary Systems
Working Group Report
Pathways to Habitable Planets
15 September, 2009
Different Flavors of Planet Formation
Typical Disk Parameters
Parameter
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
Temperature law [T(r) ~ r-q]
2-3 Myr
0.6
1-6 Myr
0.4-0.7
Parameter
Median
~1σ Range
R(inner)
R(outer)
Surface density power [Σ(r) ~ r-p]
[Hayashi min. mass solar
nebula]
[steady state viscous α disk]
Surface
density norm. Σo (5AU)
Taken from (or interpolated/extrapolated from):
0.1 AU
200 AU
0.6
1.5
1.0
~0.08-0.4 AU
~90-480 AU
0.2-1.0
(predicted)
(predicted)
14 g cm-2
±1 dex
Muzerolle et al. (2003), Andrews & Williams (2007), Hernandez et al. (2008), Isella et al. (2009)
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)
Disk Evolution in Upper Sco at 5 Myr: 220 Stars
=> Primordial disks last
longer around lower
mass stars.
=> Duration of the
“transition” ~105 yrs.
Carpenter et al. (submitted)
 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!
CAIs Vesta/Mars
Chondrules
Earth-Moon
LHB
0.0
0.1
0.2
0.3
0.4
Evolution of Disks Around Sun-like Stars:
Tracing Planet Formation? (Field & Cluster)
6.0
7.0
8.0
9.0
Siegler et al. ‘07; Currie et al. ‘07; Meyer et al. ‘08; Carpenter et al. ‘09
QuickT ime™ and a
TIF F (Uncompressed) decompressor
are needed t o 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.
Lisse et al. (2009)
Such collisions are
rare in Spitzer
samples.
QuickT ime™ and a
TIF F (Uncompressed) decompressor
are needed t o see this picture.
…you can see
them with next
generation
instruments!
Miller-Ricci,
Meyer,
Seager,
Elkins-Tanton
(2009)
Planetesimal Dynamics = Compositional Differences
Raymond et al. (2004; 2006); Bond et al. (submitted)
The connection between planetesimal belts and
presence/absence of giant planets is not clear.
Time
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
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
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.