Forming Binary Near-Earth Asteroids From Tidal Disruptions

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the binary orbit, and has significant contributions out near 180 ◦ . The spin rates for theprimaries of the T-EEBs are much more distributed than for T-PROS, and the secondarieshave a similar distribution to that of all secondaries (not shown).2.3.3 Classes of disruptionThe three classes of disruption (S-, B-, and M-class; see Section 2.3.1) form binarieswhich have different properties. As well, each class of disruption prefers to form binariesfrom different types of encounters. First, the more disruptive the encounter, the morelikely it was to have been produced by a low q or low v ∞ encounter. Figures 2.10a,b showthe relative contributions each of the three classes made as a function of q and v ∞ . Theresultant binaries from each class had some physical differences, mostly in eccentricityand size ratio. Mild encounters had a stronger peak in high eccentricity, as compared tothe S-class disruptions where a 0.95 eccentricity was only slightly more likely to occurthan anything > 0.25 (Fig. 2.10c). This trend continues in size ratio with mild encountersproducing a strong peak between 0.1 and 0.2, while disruptive S-class encounters werepeaked at 0.9–1.0 (Fig. 2.10d).2.3.4 3 h spin rate subsetThe subset of simulations run with a progenitor 3 h spin period was done to investigatethe relationship between the progenitor spin and the binary primary spin period. Of the 3h simulations run, using only elongations of 1.0 and 1.25, 798 binaries were formed from13,000 simulations. The 3 h subset produced a similar primary spin distribution to that ofthe entire set of simulations, with none below 3.7 h period (Fig. 2.11). Overall the periodsfor the primary and secondary were essentially the same for the full parameter simulation.This result suggests that primary spin is not strongly dependent on progenitor spin, andis likely dominated by other factors such as bulk density, particle shape or small internal47
Figure 2.10: Comparison of S-class (gray fill), B-class (wide cross-hatch) and M-class(small cross hatch) tidal disruptions in terms of relative number of binaries formed foreach class. (a) The three classes are plotted as a function of close approach q and (b) v ∞ .The binaries produced within each class are also plotted as a function of (c) eccentricityand (d) size ratio of the secondary to the primary.48
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AbstractTitle of Dissertation:Formi
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Forming Binary Near-Earth Asteroids
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PrefaceMuch of the work in this dis
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AcknowledgementsI would not have ma
Page 9 and 10: 2.3 Results and Discussion . . . .
Page 11 and 12: List of Tables1.1 Binary NEA proper
Page 13 and 14: 4.8 Percentage of migrated binaries
Page 15 and 16: of the system mass M by way of Kepl
Page 17 and 18: the largest lightcurve amplitudes o
Page 19 and 20: 1.1.3 Binary Main-Belt asteroidsRec
Page 21 and 22: Lightcurve discoveriesA lightcurve
Page 23 and 24: Figure 1.1: (Top) The primary rotat
Page 25 and 26: 1.2.1 CaptureIn this scenario two a
Page 27 and 28: ever, understanding the mechanism i
Page 29 and 30: off the equator or off one end of a
Page 31 and 32: 3 Denotes a secure result with no a
Page 33 and 34: nostic.Recent results have demonstr
Page 35 and 36: another intermediate source of NEAs
Page 37 and 38: 1.5.2 Rubble pilesThe evidence for
Page 39 and 40: Chapter 2Formation of Binary Astero
Page 41 and 42: ∼ 60%, making a bulk density of
Page 43 and 44: shedding mass and distorting prior
Page 45 and 46: Figure 2.3: Snapshots of a tidal di
Page 47 and 48: Figure 2.4: Normalized probability
Page 49 and 50: Figure 2.5: Normalized probability
Page 51 and 52: Figure 2.6: (a) Satellite eccentric
Page 53 and 54: various complications of measuring
Page 55 and 56: etween ω pri and L bin ), with clo
Page 57 and 58: prolate-like), the oblate-like bodi
Page 59: Figure 2.9: Plots comparing T-PROS
Page 63 and 64: 2.3.5 Triples and hierarchical syst
Page 65 and 66: a/R pri based on a simple conversio
Page 67 and 68: Figure 2.13: The eccentricity dampi
Page 69 and 70: Main Belt. Work by Chauvineau & Far
Page 71 and 72: (1992), with a target range of slig
Page 73 and 74: The observations were made from the
Page 75 and 76: peaked period, with a lower signifi
Page 77 and 78: and suggests that it is possibly a
Page 79 and 80: fit for the period of the lightcurv
Page 81 and 82: Table 3.2.Orbital, physical and lig
Page 83 and 84: Figure 3.2: Asteroid lightcurves.70
Page 85 and 86: Figure 3.4: Asteroid lightcurves.72
Page 87 and 88: 3.4.4 Spin and shape properties amo
Page 89 and 90: Figure 3.7: The lightcurve amplitud
Page 91 and 92: Typically observations of eclipse o
Page 93 and 94: Chapter 4Steady-State Model of the
Page 95 and 96: values between 0.2-0.6. There is on
Page 97 and 98: asteroids in the Main Belt is suffi
Page 99 and 100: Figure 4.2: Percent of surviving NE
Page 101 and 102: 4.1.3 Binary evolutionBasic stabili
Page 103 and 104: Table 4.1.Lifetimes for binary NEAs
Page 105 and 106: which means it should have a critic
Page 107 and 108: Figure 4.4: The total number of bin
Page 109 and 110: the original eccentricity distribut
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Figure 4.6: Properties of the binar
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Figure 4.8: Binary percentage for m
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Figure 4.9: Effects of tidal evolut
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quickly altered, or involved in bin
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tidal disruption. However, the impl
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Chapter 5ConclusionsA general concl
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small additions to the angular mome
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cently this large pool of observers
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differences in results when a lower
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Table A.1.Number of binaries produc
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Thus the reaccumulated bodies in th
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of 2.2 h observed is significantly
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Benner, L. A. M., Nolan, M. C., Ost
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V7.0:LCREF TAB, 35, 4Harris, A. W.,
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Storrs, A. D., Close, L. M., & Mena
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122Pravec, P., Kušnirá, P., Hicks
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Shepard, M. K., Schlieder, J., Nola
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Forming Binary Near-Earth Asteroids From Tidal Disruptions

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