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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
Formation of Phobos and Deimos via a Giant Overview of Citron et - - PowerPoint PPT Presentation
Formation of Phobos and Deimos via a Giant Overview of Citron et - - PowerPoint PPT Presentation
Formation of Phobos & Deimos Harrison Agrusa Formation of Phobos and Deimos via a Giant Overview of Citron et al. Impact 2015 Stuff I did Harrison Agrusa Based on the paper by Citron, Genda & Ida 2015 December 9, 2018 Overview
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
The Martian Crustal Dichotomy
A giant impact could explain the Martian dichotomy. Marinova et al. 2008 found initial conditions needed to form present day dichotomy. Citron et al. 2015 want to kill two birds with one
- stone. Can those same
intial conditions create a debris disk large enough to form Phobos and Deimos?
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
How to form Phobos and Diemos through a giant impact
The mass of all past and present satellites can be inferred from the population of elongated craters. (Schultz et al. 1982)
Msats „ 10´6 ´ 2 ˆ 10´5MD
Rosenblatt & Charnoz 2012 model circum-Mars disk evolution in strong and week tidal regimes.
Mdisk „ 100Msats
Marinova et al. 2008 find that Mimp „ 0.026MD with vimp „ 1.4vescis needed to produce Martiain dichotomy. Putting all this together, we have:
Mdisk Mimp „ Msats Mimp Mdisk Msats „ 0.004 ´ 0.08
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
SPH Simulations
Citron et al. 2015 sets out to compute Mdisk{Mimp with SPH simulations. In all simulations, their disk mass agrees with theory. In nominal case they have Mdisk „ 0.033Mimp.
Nominal Initial Conditions N 3 ˆ 105 Mimp 1.68 ˆ 1022 kg vimp 1.4vesc „ 6 km/s θ 45˝
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
My extension
Interested in the dependence of disk mass on the impact angle. Reproduce these simulations at higher resolution with Spheral++: Failed, not feasible to set up in time Reproduce these simulations with pkdgrav: Failed, can’t handle high energy impact Scale simulations down to a regime where pkdgrav can work: It worked?
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
Giant Impact on Ceres!
MT „ 9.39ˆ20 kg 18 Simulations over angles from 0 to 85 degrees Should expect minimum disk masses at 0 and 90 degrees, and some peak disk mass somewhere in the middle. Citron et al. Me et al. Mimp 0.028MT „ 1.68 ˆ 1022 kg 0.028MT „ 3.38 ˆ 1018 kg vimp 1.4vesc „ 6 km/s 1.4vesc „ 0.71 km/s
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did
Results
50 100 150 200 250
Time [minutes]
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Mdisk Mimp
Disk Mass vs. Time
Impact Angle [Degrees]
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
20 40 60 80 0.08 0.09 0.10 0.11 0.12 0.13
Mdisk Mimp
0.018 0.020 0.022 0.024 0.026 0.028 0.030 0.032
Mdisk Mimp
Final Disk Mass vs. Impact Angle
Final Disk Mass [Citron 2015]
The bad: Runs not quite done (run on machines of differing speeds) Need way more particles, but thats okay so does Citron et al. Bodies constructed with hexagonal close packing, systematic errors expected Target and Impactor do not have equal sized particles The Good: Got the trend I was looking for... I think? Cool animation: https://youtu.be/O_G9O-oXYY8
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Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did