SLIDE 1
Observing Planet Formation: The Impact of Collisions
Zoë M. Leinhardt Jack Dobinson, Phil Carter, Stefan Lines School of Physics University of Bristol, UK
Observing Planet Formation: The Impact of Collisions Zo M. Leinhardt - - PowerPoint PPT Presentation
Observing Planet Formation: The Impact of Collisions Zo M. Leinhardt - - PowerPoint PPT Presentation
Observing Planet Formation: The Impact of Collisions Zo M. Leinhardt Jack Dobinson, Phil Carter, Stefan Lines School of Physics University of Bristol, UK Snapshots from Observations Hubble Space Telescope Orion Nebula Proplyd Atlas 2009
SLIDE 2
SLIDE 3
Snapshots from Observations
10 100 1.0 0.1 0.01 10 1.0 0.1 0.01 1e-3 1e-4 100
Semi-major Axis [AU] Mass x sin(i) [MJ]
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Planet Formation Cartoon
Molecular Cloud (H2) [Orion Nebula] Accretion Disk & Young Star [Proplyds] Mature Star & Planets [HR 8799]
This is the process that we would like to
- understand. It is
effectively invisible.
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Planetesimal Collision Outcomes
Planetesimals in the gravity regime > 1km Evolution code: PKDGRAV (N-body) Collision model: EDACM
Perfect Merge Catastrophic Disruption Hit-&-Run Partial Disruption
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Empirically Derived Analytic Collision Model (EDACM)
Leinhardt & Stewart 2012
rubble piles, 1-50 km
Leinhardt & Stewart 2009, Leinhardt et al. 2000
ice, 50 km
(LS09)
basalt, 1-100 km
(Benz & Asphaug ’99)
basalt, 2-50 km (LS09) basalt
(Jutzi et al. ‘10)
Q∗
RD = qs (S/ρ1)3¯ µ(φ+3)/(2φ+3) R9¯ µ/(3−2φ) C1
V ∗(2−3¯
µ) + qg (ρ1G)3¯ µ/2 R3¯ µ C1V ∗(2−3¯ µ)
Strength Regime Gravity Regime
Coupling parameter ~ 0.35 momentum scaling Material specific parameter
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Specific impact energy
Vi θ αMp
, ,
t
M c µ
∗
Radius of total mass (km)
U = Gravitational binding energy
*
for
R D p t
Q c U M M
∗
= =
+ +
1
p t
M M <
+
θ >
* (J/kg) RD
Q
*
V
( )
* *
, , , , ,
RD tot p t
Q c M M M V θ µ
∗
= F
0.50 0.70 0.86 1 Impact Parameter b 0.50 0.70 0.86 1 Impact Parameter b 30 45 60 90 θ [deg] 5 10 15 20 V
i / V esc
Mp:Mt =1:10
Merging Partial Accretion Erosion Hit & Run 0.1Mt 0.9Mt 0.5Mtot Mt+0.5Mp
( )
* , lr tot R RD
M M Q Q η = F
1 2 3 4 5
QR/Q*
RD
0.0 0.2 0.4 0.6 0.8 1.0
Mlr/ Mtot
Linear near Q*RD
Power law slope η for QR > 1.8Q*RD
- A. Collision parameters B. Catastrophic disruption criteria
- C. Mass of the largest remnant D. Maps of collision outcomes
( ) ( )
2
( ) 2
p t p t i R p t
M M M M V Q M M α α α + = +
Leinhardt & Stewart (2012)
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Numerical Method: Quiet Terrestrial Planet Formation
- 1. Evolution code:
N-body gravity code PKDGRAV
- 2. Collision Model:
a) perfect merging; b) RUBBLE; c) EDACM
- 3. Planetesimal disk:
Standard surface density (MMSN) Ʃ = Ʃ1(a/1AU)-1.5, Ʃ1 =10 g/cm2 0.5 < a < 1.5 AU Ninit = 104, R ~ 100 km, f = 6 No gas
+
Desktop Planetesimal disk
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Results: Formation of Embryos
Leinhardt et al. in press
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Results: Degree of Planetesimal Mixing
RUBBLE EDACM Semi-Major Axis [AU] 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
Embryo Composition at 400,000 yr (14.4 Myr)
- Each colour shows amount (% mass) of material both resolved and
unresolved accreted from a particular semi-major axis
- Both RUBBLE and EDACM show limited mixing
Leinhardt et al. in press
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Results: Planetesimal Collision Outcomes
Leinhardt et al. in press
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Results: Instantaneous Dust Images
50,000 (1.8 Myr) 100,000 (3.6 Myr) 200,000 (7.2 Myr) 400,000 (14.4 Myr) Unresolved Debris Surface Density RADMC3D Flux (850 μm) 1x106
- Jy/sr
Quiet runaway and oligarchic growth not observationally visible with ALMA But what if the scenario is not quiet? What if there is a perturber?
Leinhardt et al. in press
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Transitional (& Pre-transitional) Disks
MWC 758 PDS 70, pre-transitional disk Hashimoto et al. 2012 Grady et al. 2013 Muto et al. 2012 SAO 206462 Kraus & Ireland 2012
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Numerical Method: Quiet Terrestrial Planet Formation
- 1. Evolution code:
N-body gravity code PKDGRAV
- 2. Collision Model:
EDACM+
- 3. Planetesimal disk:
Standard surface density (MMSN) Ʃ = Ʃ1(a/1AU)-1.5, Ʃ1 =10 g/cm2 0.5 < a < 10 AU Ninit = 106, R ~ 100 km, f = 1 Gas, Jupiter-mass planet @ 2.8 AU
Bluecrystal Supercomputer UoB
+
Planetesimal disk
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Numerical Method: EDACM+
Resolved Rubble-pile Collision EDACM+ v = 50 m/s, b = 0.9 v = 38 m/s, b = 0.0 Mp/Mt = 0.25
Leinhardt et al. in press
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Results: Collisional Stirring from a Circular Planet
Dobinson, Leinhardt et al. in prep.
10xMaxNoPlanet 0.0
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Results: Planetesimal Collision Outcomes
No Planet (control) Circular Planet Eccentric Planet (e=0.1) Eccentric Planet (e=0.2)
Dobinson, Leinhardt et al. in prep.
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Results: Collisional Stirring from an Eccentric Planet
Dobinson, Leinhardt et al. in prep.
10xMaxNoPlanet 0.0
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Conclusions & Caveats
- Our current work suggests it will be hard to observe planetesimal
evolution if the growth environment is dynamically quiet
- A more active environment such as an embedded planet increases
dynamical temperature will result in more debris
- No primordial dust - needed to create most realistic synthetic images
- working on it
- In transitional disk work - just one planet - wide gap transitional disks
would require more than one
- Location of the planet picked to make simulations numerically