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WE PROPOSE A COMPREHENSIVE SUITE OF NUMERICAL SIMULATIONS TO INVESTIGATE THE FORMATION OF PLUTO'S SMALL SATELLITES. THIS PROGRAM ADDRESSES KEY ISSUES IN THE FORMATION ACCRETION STABILITY AND DYNAMICAL EVOLUTION OF SOLAR SYSTEM BODIES THROUGHOUT THE HISTORY OF THE SOLAR SYSTEM. WE FOCUS ON THE GIANT IMPACT HYPOTHESIS WHERE A ROUGHLY CHARON MASS PROTOPLANET COLLIDES WITH A ROUGHLY PLUTO MASS PROTOPLANET. IN THE MOST POPULAR OUTCOME THE COLLISION YIELDS A BINARY PLANET SURROUNDED BY A MODEST CLOUD OF DEBRIS WHICH EVOLVES INTO A SET OF LOW MASS SATELLITES. IN THIS SCENARIO IT IS UNCLEAR WHETHER LOW MASS SATELLITES CAN FORM IN THE DEBRIS AND HOW THEY MIGHT SURVIVE TIDAL EXPANSION OF THE BINARY. OUR GOAL IS TO EMPLOY ORCHESTRA OUR HYBRID COAGULATION + N-BODY CODE TO ADDRESS THESE ISSUES. ORCHESTRA INCLUDES A MULTI-ANNULUS COAGULATION/DIFFUSION CODE AND AN N-BODY CODE WHICH TREATS THE LONG-TERM EVOLUTION OF A SWARM OF SOLID PARTICLES ORBITING A CENTRAL MASS. THE CENTRAL MASS CAN BE SINGLE OR BINARY. THE COAGULATION/DIFFUSION CODE USES A STATISTICAL APPROACH TO TREAT PHYSICAL COLLISIONS AND GRAVITATIONAL INTERACTIONS OF SOLIDS AND OUTPUTS THE TIME EVOLUTION OF THE DISTRIBUTIONS OF THE NUMBER (N) AND ORBITAL PARAMETERS (A E AND I) OF PARTICLES WITH SIZES RANGING FROM 1 MICRON UP TO ROUGHLY 1% OF THE MASS OF THE CENTRAL OBJECT(S). THE N-BODY CODE FOLLOWS THE REAL-TIME TRAJECTORIES OF MASSIVE PARTICLES. MASSLESS TRACER PARTICLES WHICH RESPOND TO THE CHANGING GRAVITATIONAL POTENTIAL OF THE N-BODIES AND THE GRAVITATIONAL INTERACTIONS OF MASS BINS IN THE COAGULATION CODE ALLOW US TO LINK THE EVOLUTION OF PARTICLES IN THE TWO CODES ENABLING A ROBUST CALCULATION OF PLANET/SATELLITE FORMATION THAT FOLLOWS ALL OF THE MASS AS A FUNCTION OF TIME. OUR APPROACH ALLOWS US TO ISOLATE THE IMPORTANCE OF FRAGMENTATION GRAVITATIONAL STIRRING MIGRATION AND THE TIME-VARYING POTENTIAL OF THE BINARY IN THE EVOLUTION OF A CIRCUMBINARY SATELLITE SYSTEM.FOR THIS PROPOSAL WE PLAN TO BUILD ON PREVIOUSLY SUCCESSFUL STUDIES OF THE FORMATION OF SMALL SATELLITES IN A RING SURROUNDING A SINGLE OBJECT WITH THE MASS OF PLUTO-CHARON (KENYON&BROMLEY AJ 147:8) THE MIGRATION OF SMALL SATELLITES THROUGH DEBRIS SURROUNDING A BINARY (AJ 147:8) AND THE EXPANSION OF A RING OF DEBRIS SURROUNDING A BINARY (BROMLEY&KENYON APJ 809:88). WE WILL INVESTIGATE THE FORMATION AND ORBITAL EVOLUTION OF SATELLITES WITHIN AN EXPANDING RING OF DEBRIS SURROUNDING AN EXPANDING BINARY. THIS STUDY WILL COMBINE THE APPROACHES USED IN OUR TWO PREVIOUS INVESTIGATIONS INTO A SINGLE THEORY FOR SATELLITE FORMATION. ASSUMING STANDARD MODELS FOR THE EVOLUTION OF THE CENTRAL BINARY WE WILL CONSIDER VARIOUS INITIAL CONDITIONS FOR THE TOTAL MASS ORBITS AND THE SIZE/ VELOCITY DISTRIBUTIONS OF RING MATERIAL WHICH ARE GENERALLY CONSISTENT WITH THE OUTCOMES OF GIANT IMPACT MODELS (E.G. CANUP AJ 141:35). OUR NUMERICAL SIMULATIONS WILL YIELD THE MASSES AND ORBITAL PARAMETERS FOR SATELLITES AS A FUNCTION OF TIME. COMPARISONS OF THEORETICAL OUTCOMES WITH THE NUMBER AND THE PROPERTIES OF KNOWN SATELLITES DERIVED FROM HUBBLE SPACE TELESCOPE AND NEW HORIZONS OBSERVATIONS WILL ALLOW US TO IDENTIFY THE SUBSET OF INITIAL CONDITIONS CAPABLE OF PRODUCING OBJECTS SIMILAR TO THE KNOWN SATELLITES. BASED ON PREVIOUS EXPERIENCE WE EXPECT THIS SUBSET TO BE REASONABLY SMALL. THUS OUR INVESTIGATION WILL PLACE STRONG CONSTRAINTS ON GIANT IMPACT MODELS OF SATELLITE FORMATION.

$199,351FY2017National Aeronautics and Space AdministrationNASA

Smithsonian Institution, Washington DC

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