Formation and Evolution of
Planetary Systems:
The Makings of an
Epicurean Feast
Michael R. Meyer
Steward Observatory, The University of Arizona
Solar/Extra-solar Planet Meeting
February 4, 2009, NASA-Ames Research Center
Are planetary systems like our own are common or
rare 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
Planetary debris
disk ~ 100 Myr old
Solar system debris
disk 4.56 Gyr old!
12
Gas-rich disk ~ 1 Myr old
Different Wavelengths Trace Different Radii!
NIR
MID
FIR
0.1 1.0
10.0
sub-mm
100 AU
Star with
magnetospheric
accretion columns
Accretion disk
Disk driven
bipolar outflow
Infalling
envelope
Terrestrial Planets?
Chrondrules?
CAI Formation?
Inner (< 0.1 AU) Accretion Disk Evolution 0.1-10 Myr
Does the observed
range in initial disk
mass (e.g. Andrews &
Williams, 2005)
explain the observed
range in disk
lifetimes?
Haisch et al. 2001;
Hillenbrand et al. (2002);
Muzerolle et al. (2003).
Haisch et al. 2001;
Hillenbrand et al. (2002);
Muzerolle et al. (2003).
< t > ~ 3 Myr
Frequency
Terrestrial Planets?
Chrondrules?
CAI Formation?
Inner (< 0.1 AU) Accretion Disk Evolution 0.1-10 Myr
Inner Disk Lifetime
Solar System History
from Radioactive
Nuclides
E. Scott (2007)
Chondrules & Protoplanetary Disks
S. Jacobsen (2005)
Earth-Moon System Formation
Rapid Transition time thick to (very) thin inside 1 AU
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.
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)
Dynamics and Chemistry of Protostars & Disks:
Gas Phase Spectroscopy with VLT, Herschel, and ALMA
Dutry et al. (1997)
Lahuis et al. (2006)
Saylk et al. (2007)
Qi et al. (2007)
Najita et al. (2007)
HIFI-Team (soon)
VLT Resolution is ~ 6 AU
at 4 µm of nearest targets
at 50 parsecs (e.g. TW Hya).
Yorke & Bodenheimer (1999)
Planet-forming Disks:
Molecular Abundances vs. Radius
Courtesy J. Najita & S. Strom (NOAO)
See also Pontoppidan et al. (2008)
Simulation
DQ Tau: Carr, Mathieu & Najita (2001)
Gas disk chemistry may vary with stellar mass…
Pascucci et al. (in press); cf. Carr & Najita (2008)
FUV and (or?) X-rays in action…
Pascucci et al. (2007); Esplainat et al. (2007); Herzeg et al. (2007)
Primordial Gas disk lifetimes appear to be < 10 Myr.
No massive gas
disks detected
around 35 stars
with ages 3-100
Myr. Less than
0.1 Mjup remains
to 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
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).]
0.4
Evolution of Disks Around Sun-like Stars:
Tracing Planet Formation? (Field & Cluster)
LHB
0.0
0.1
0.2
0.3
CAIs Vesta/Mars
Chondrules
Earth-Moon
6.0
7.0
8.0
9.0
Meyer et al. (2008); Kenyon/Bromley (2006); Siegler et al. (2007); Currie et al. ‘07
Observational Constraints on Planet Formation:
Detecting Hot Protoplanet Collision Afterglows?
Mamajek & Meyer (2007); Miller-Ricci et al. (submitted)
Dust Production
The connection between planetesimal belts and
presence/absence of giant planets is not clear.
Plan
ets
No P
lanet
Time
s
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.
Direct Detection of
Gas Giant Planets
No massive planets
at large radii around
debris disk targets
with large inner gap
Apai et al. (2008)
Circumstellar Disk Evolution and Multiplicity:
Complex Story T Tauri Binaries vs. Separation
Simon & Prato (1995); Jensen et al. (1994)
Debris Disks not inhibited
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 or
rare 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 or
rare 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.
- any evidence for warm dust gone by 300 Myr.
- 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 full
planetary systems, or those without any planets?
A Picture is Worth 1024 x 1024 Points on an SED…
But thermal IR pictures of Fomalhaut with JWST
are worth EVEN MORE!
Spitzer @ MIPS-24
JWST-MIRI
Imaging Super-Earths in 2013?
Meyer et al. (2007)
“In the Spirit of Bernard Lyot”
NIRCam Instrument (M. Rieke, PI)
FGS/TFI Instrument (R. Doyon, PI)
Diffraction Suppression Techniques:
Krist et al. (2007)
Kenworthy et al. (2007)
Sivaramakrishnan et al. 2008
The Late-Heavy Bombardment and the
Dynamical History of the Solar System
An old Fairy Tale:
New Fairy Tales...
Thommes et al. (2002)
Morbidelli et al.; Gomes et al.; and
Tsiganis et al. (2005)
Strom et al. (2005); and Bottke et al. (2005)
Planet Searches
with MMT/CLIO
A. Heinze,
P. Hinz (PI),
S. Sivanandam,
M. Kenworthy,
D. Apai,
E. Mamajek,
& M. Meyer
Background star;
equivalent in brightness
to a planet of ~5MJ.
Thermal IR enables the study of mature stars, which are
common and thus nearby, providing fine physical
resolution, and modest model uncertainties.
Direct Detection of
Gas Giant Planets
No massive planets
at large orbital radii.
[3 Mjup @ 30 AU]
dN/da ~ ap
Kasper et al. (2007);
Apai et al. (2008);
Heinze et al. (in prep)
Miller-Ricci et al.
(submitted)