Forming Binary Near-Earth Asteroids From Tidal Disruptions

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2.3.2 T-PROS and T-EEBsDurda et al. (2004) introduced terminology to differentiate between two types of satellitesformed in a collision. The SMAshed Target Satellites (SMATS) form from debris orbitingaround a remaining target body. The Escaping Ejecta Binaries (EEBs) form from fragmentsescaping the collision and becoming bound to one another. Similar analogs exist inthe case of a tidal disruption. We have dubbed systems that form around the largest remnantof the disruption “<strong>Tidal</strong> PROgenitor Satellites” (T-PROS), and those that form fromescaping debris “<strong>Tidal</strong> Escaping Ejecta Binaries” (T-EEBs). As seen in the collisionalcases, there are distinct differences between the two groups. The strongest difference isin size ratio, where the T-PROS have a high probability of having a size ratio between 0.1and 0.2, while the T-EEBs have a strong chance of being 0.8 and higher (Fig. 2.9a). Someof this effect may be due to the resolution of the simulations, where if most of the 1000particles are invested in the largest remnant, there are only limited remaining particles tocreate a T-EEB, which will then necessarily have size ratio near unity (to be considered,a clump must have at least 3 particles). This was also observed by Durda et al. (2004),where many of the EEBs are the lowest-resolution particles, thus having a size ratio ofexactly 1. With only one NEA binary (Hermes) with a size ratio above 0.7, T-EEBs maynot be common; in the simulations they made up only ∼ 10% of the total systems created,and have even stronger tendencies to come from extreme disruptions with low q and v ∞(Fig. 2.9c,d).There is also a distinct difference in the spin axis alignments for the two types (Fig.2.9b). The T-PROS’ primary spin axes are typically closely aligned with the binary orbitalangular momentum, while the T-EEBs’ primaries have only a slight correlation with theorbit. The T-PROS distribution matches that for the overall distribution, with close to 90%being aligned within 20 ◦ of the binaries’ orbits. T-EEBs show only a slight alignment with45
Figure 2.9: Plots comparing T-PROS (shaded) with T-EEBs (bold lines) in terms of relativenumber, meaning each distribution is normalized independently due to large disparityin overall numbers: (a) secondary-to-primary size ratio; (b) primary obliquity; (c) relativebinary formation as a function of encounter conditions q and (d) v ∞ .46
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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
Page 7 and 8: 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: prolate-like), the oblate-like bodi
Page 61 and 62: Figure 2.10: Comparison of S-class
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
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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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