Project Goals

1
Time constraints from the early solar system
From dust to planetesimals Ringberg Castle
11.9.2006 M. Trieloff University of
Heidelberg, Institute of Mineralogy,
Heidelberg, Germany
2
Short-lived nuclides in the early solar system
and their half-lives 26Al ? 26Mg (0.72
Ma)129I ? 129Xe (16 Ma)182Hf ? 182W (9 Ma)53Mn
? 53Cr (3.7 Ma)244Pu ? fission (80 Ma) 10Be ?
10B (1.5 Ma) 41Ca ? 41K (0.1 Ma) 60Fe ? 60Ni
(1.5 Ma) nucleosynthesis in mass-rich stars
or nuclear reactions due to solar irradiation
(10Be)
Trapezium (Orion nebula)

• ... injected into protoplanetary
• disks (solar mass)
• Radiometric dating
• Planetesimal heating

3
Ca,Al-rich Inclusions refractory mineral
assemblages, oldest solar system objects ?
4567.2 0.6 Ma (Amelin et al., 2002) 26Al.26Mg
systematics Processing within few 0.1 Ma
Young et al. 2005
4
Early formed asteroids high abundance of 26Al,
strongest heating effects ? Differentiated
meteorites from metallic cores and silicate
mantles and crusts of differentiated asteroids
Hf
W
182Hf? 182W

• Fast accretion and differentiation
• formation of metallic cores contemporaneously
  with CAIs (182Hf-182W Kleine et al., 2004)
• formation and cooling of basaltic crust within
  few Ma (Eucrites, Angrites Pb-Pb-dating e.g.
  Lugmair and Galer, 1992 Baker et al.,. 2005)

5
Ordinary chondrites (H, L, LL) significant
thermal metamorphism by 26Al decay heat
H4 Chondrite (650C)
H6 Chondrite (850C)
6
(Göpel et al., 1994)
Time b.p. Ma
7
Carbonaceous chondrites (CI, CM, CV, CO, )
only mild heating effects by 26Al decay /
(thermal/aqueous metamorphism) ?preaccretional
structures preserved
4564.7 0.6 Ma (CR Acfer059
Amelin et al., 2002)

• Chondrules

2-3 Ma age difference supported by 26Al-26Mg
chronometry

• Ca,Al-rich inclusions

4567.2 0.6 Ma (U-Pb-Pb, CV Efremovka
Amelin et al., 2002)
Allende
8
Chronology of the Early solar system Calibratio
n of short-lived nuclide chronometers relative
to U-Pb-Pb 26Al ? 26Mg (0.72 Ma)129I ? 129Xe
(16 Ma)53Mn ? 53Cr (3.7 Ma)26Al heating model
ages (Trieloff Palme, 2006)
9
Collaps of protosolar nebula, injection of
short-lived nuclides, dust grain growth by
coagulation
4567,2 Ma CAIs, Chondrules, Planetesimals
(strong heating, differentiation)

• 2 bis 4 Ma Chondrules, Planetesimals (mild
  heating, no differentiation)

10
Main Earth mass (?63) after 12 Ma
Earth complete core formation means complete
(?99 ) accretion
Mars 99 after 10 Ma, 63 after 2-3 Ma
Kleine et al., 2002 Yin et al., 2002 Halliday
et al., 2004
11
Collaps of protosolar nebula, injection of
short-lived nuclides, dust grain growth by
coagulation
4567,2 Ma CAIs, Chondrules, Planetesimals
(heating, differentiation)

• 2 bis 4 Ma Chondrules, Planetesimals, moderate
  heating, no differentiation)

• Proto-Mars present
• ? Jupiter present
• Jupiter migration?
• (disk-planet interaction)

12
Disappearance of dust disk lt6 Ma (Haisch et
al. 2001)
13
Collaps of protosolar nebula, injection of
short-lived nuclides, dust grain growth by
coagulation
4567,2 Ma CAIs, Chondrules, Planetesimals
(heating, differentiation)
fine dust

• 2 bis 4 Ma Chondrules, Planetesimals, moderate
  heating, no differentiation)

• Proto-Mars present
• ? Jupiter present
• Jupiter migration?

• Loss of disk
• Fine dust 3-6 Ma
• (Haisch et al., 2001)
• Gas few Ma, few tens Ma ?
• (Thi et al., 2001 Briceno et al., 2001)
• Inner disk gas loss few Ma
• H-alpha emission correlates with IR
• dust signal (Briceno et al., 2001)

14
Likely candidate mechanism for disk loss
Photoevaporation (Alexander et al. 2006)
15
Evidence for syn-accretionary solar wind
irradiation in early solar system solar wind
neon in Earths mantle
16
Collaps of protosolar nebula, injection of
short-lived nuclides, dust grain growth by
coagulation
4567,2 Ma CAIs, Chondrules, Planetesimals
(heating, differentiation)
gas
fine dust

• 2 bis 4 Ma Chondrules, Planetesimals, moderate
  heating, no differentiation)

• Proto-Mars present
• ? Jupiter present
• dust and gas loss/ irradiation effects in inner
  disk
• (Earth precursor planetesimals,
• some meteorite parent bodies)

17

• What determines speed of planetesimal formation
  via coagulation?
• Critical sizes / relative velocities (m-size
  barrier ? experiments)
• Effect of mass density
• Solar system gradient higher mass density in
  inner solar system, i.e. faster formation of
  inner solar system planetesimals
• Bottke et al. 2006 iron meteorites are from
  planetesimals scattered from the inner solar
  system into the asteroid belt

18

• What determines speed of planetesimal formation
  via coagulation?
• Effect of mass density
• Chondrule/Chondrite formation requires enhanced
  dust /gas ratios
• e.g. Cuzzi Alexander (2006)
• lack of isotopic fractionation requires that
  local heating chondrule formation partial
  evaporation occurred under closed system
  conditions and sufficient high densities in order
  to warrant isotopic exchange
• Chondrules formed in clouds 150 6000 km size,
  with ?10 chondrules m-3
• Material in dust enriched regions of these size
  sufficient for small planetesimals (few km)
• Concentration in nebula turbulence (rather than
  simple midplane settling)
• Other large scale concentration mechanisms
  equally viable (vortices, photophoretic effects)

19

• Constraints on chondrule formation/heating
  mechanisms
• What causes local heating?
• High density excludes off-disk mechanism (e.g.
  x-ray flare shocks, clumpy accretion) and favours
  regions close to midplane
• Large diameter of regions excludes small scale
  events lightning, asteroid shock waves and
  favours solar system wide shock waves

20
Once chondrules formed, chondritic planetesimals
from fast Chemical cmplementarity requires that
matrix and chondrules of specific chondrites
formed from Mg/Si solar precursor material, and
were not separated (e.g. radial drift !) before
chondrite accretion, i.e growth timescales ltlt
radial drift timescales
CV chondrules
CR chondrules
CAIs, - volatiles
- CAIs ?
0
40
15
37
55
20
chondrules
forsterite-enstatite fractionation
CV matrix
CR matrix
21
CV3 Efremovka
chondrules
Hezel, Palme Kießwetter in prep.
matrix
22
Klerner, Palme, 2000
23

• Conclusions
• Well developped framework of early solar system
  chronology based on radioisotope chronometry
• Formation of small planetesimals within few Ma,
  within disk lifetime

• Remaining problems
• Hierarchical growth from dust to protoplanets
  could be
• fast theoretically and occurred probably
  fast for individual meteorite parent bodies
  (within lt 1 Ma), but some planetesimals formed
  earlier, some later
• Due to critical growth phases, e.g. collisional
  destruction in m-size regime (few m/s relative
  velocity) ?
• Certain conditions suitable to overcome critical
  growth phases/ trigger growth ? Dust enrichments,
  Chondrule forming processes, photoevaporation
  (Throop and Bally 2005), photophoresis (Wurm and
  Kraus, 2005), others .?

24
Processed grains as probes for radial mixing in
protoplanetary discs and STARDUST From dust to
planetesimals Ringberg Castle 11.9.2006
25
IR spectroscopy of protoplanetary disks Mg
silicates olivinepyroxene crystalline fraction
higher in inner disks (van Boekel et al. 2004)
40 - 20
15 - 10
55 - 25
10 - 5
40 - 15
95 - 10
26

• Crystalline fractions in some outer disks
  considerable, similar to solar system comets
• (Wooden et al., 2000)
• Dust processing in disks and radial mixing into
  outer disks

IR spectroscopy of protoplanetary disks Mg
silicates olivinepyroxene crystalline fraction
higher in inner disks (van Boekel et al. 2004)
27
Models taking into account annealing,
evaporation, and condensation of Mg silicates
reproduce radial mixing of crystalline species
into outer disk /comet forming regions (Gail 2003)
28
Bulk chondrite chemistry indicates fractionation
between refractories/volatiles, Mg-silicates
(Fo/En), silicate and metal
CAIs
- CAIs
forsterite-enstatite fractionation
29
Interplanetary dust particle (cometary?)
30
Interplanetary dust particle (cometary?)

• Oxygen isotopic composition measured with the
  nanoSIMS (St. Louis, Mainz)
• evidence for lt0.5 unequilibrated interstellar
  silicates (crystalline Mg-rich, and GEMS)
• normalcrystalline grains high temperature
  origin close to early sun, subsequent radial
  mixing into outer solar system
• normal GEMS formation in cold regions of solar
  nebula /ISM ?
• anomalous silicates memorize stellar source
  (crystalline grains?)

31
IDP Aurelian by TOF-SIMS (left and center bottom)
and NanoSIMS (right) 15 N-rich material is
associated with silicate material with high
Mg/Fe-ratios (center bottom), presumably
forsterite
32
Cometary grains from comet Wild-2 returned by the
STARDUST mission
Refractory forsterite grain from STARDUST
collector
First results Silicates (Olv, Px, Fs), glass,
Fe-Ni sulfides, refractory grains (An,Di,Sp) no
phyllosilicates and carbonates in Wild-2 grains
33

• STARDUST ? identify cometary IDP population
• Quantify isotopically anomalous/normal grains
• Proportion of cometary grains processed in the
  inner early solar system
• Constraints on radial mixing in disk models