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 Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 1 Overview of Citron et al. 2015 Stuff I did 2 Stuff I did

The Martian Crustal Dichotomy Formation of Phobos & Deimos A giant impact could Harrison explain the Martian Agrusa dichotomy. Overview of Citron et al. Marinova et al. 2008 2015 found initial conditions Stuff I did 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?

How to form Phobos and Diemos through a giant impact Formation of Phobos & Deimos The mass of all past and present satellites can be inferred Harrison Agrusa from the population of elongated craters. (Schultz et al. 1982) Overview of Citron et al. M sats „ 10 ´ 6 ´ 2 ˆ 10 ´ 5 M D 2015 Rosenblatt & Charnoz 2012 model circum-Mars disk Stuff I did evolution in strong and week tidal regimes. M disk „ 100 M sats Marinova et al. 2008 find that M imp „ 0 . 026 M D with v imp „ 1 . 4 v esc is needed to produce Martiain dichotomy. Putting all this together, we have: M disk M disk M imp „ M sats M sats „ 0 . 004 ´ 0 . 08 M imp

SPH Simulations Formation of Citron et al. 2015 sets out to compute M disk { M imp with Phobos & Deimos SPH simulations. Harrison Agrusa In all simulations, their disk mass agrees with theory. In nominal case they have M disk „ 0 . 033 M imp . Overview of Citron et al. 2015 Stuff I did Nominal Initial Conditions 3 ˆ 10 5 N 1 . 68 ˆ 10 22 kg M imp v imp 1 . 4 v esc „ 6 km/s θ 45 ˝

My extension Formation of Phobos & Deimos Harrison Agrusa Interested in the dependence of disk mass on the impact Overview of angle. Citron et al. 2015 Reproduce these simulations at higher resolution with Stuff I did 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?

Giant Impact on Ceres! Formation of Phobos & Deimos Harrison Agrusa M T „ 9 . 39 ˆ 20 kg Overview of Citron et al. 18 Simulations over angles from 0 to 85 degrees 2015 Stuff I did 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. 0 . 028 M T „ 1 . 68 ˆ 10 22 kg 0 . 028 M T „ 3 . 38 ˆ 10 18 kg M imp v imp 1 . 4 v esc „ 6 km/s 1 . 4 v esc „ 0 . 71 km/s

Results Formation of Disk Mass vs. Time Final Disk Mass vs. Impact Angle Phobos & 0 . 7 Impact Angle [Degrees] Deimos Final Disk Mass [Citron 2015] 0 30 60 0 . 13 0 . 032 5 35 65 0 . 6 10 40 70 Harrison 15 45 75 20 50 80 0 . 030 Agrusa 0 . 12 25 55 85 0 . 5 0 . 028 M disk 0 . 4 0 . 11 M disk Overview of M imp 0 . 026 M imp Citron et al. M disk 0 . 3 0 . 024 M imp 2015 0 . 10 0 . 2 0 . 022 Stuff I did 0 . 09 0 . 1 0 . 020 0 . 08 0 . 0 0 . 018 0 50 100 150 200 250 Time [minutes] 0 20 40 60 80 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

El Fin Formation of Phobos & Deimos Harrison Agrusa Overview of Citron et al. 2015 Stuff I did