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NAM2012 - All Presentation Details

Record 532 of 756

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Spectroscopic Observations of Unbound Asteroid Pairs

Author: Samuel Duddy

School of Physical Sciences, University of Kent

Co-Authors: S.C. Lowry (School of Physical Sciences, University of Kent), S.D. Wolters (Planetary Sciences Section, Jet Propulsion Laboratory), B. Rozitis (Planetary and Space Sciences, The Open University), S.F. Green, (Planetary and Space Sciences, The Open University), A. Christou (Armagh Observatory), P. Weissman (Planetary Sciences Section, Jet Propulsion Laboratory)

Session: PL1: Small bodies in Our Solar System

Presentation type: Talk      10:46  Tuesday 27th 10:00-11:15 

Summary:

Asteroids larger than a few hundred metres in diameter are believed to be loose assemblages with little internal strength, held together by their own self-gravity. If pushed beyond their natural spin limit via rotational spin-up by YORP, these asteroids could undergo fission or equatorial mass loss producing a binary system [1,2]. Models have indicated that if the mass ratio of the components of this binary is less than 0.2 then the secondary asteroid (the satellite) can escape the gravitational potential of the primary and decouple from their mutual orbit at low relative velocity [2,3]. The result is two asteroids on very similar independent orbits about the sun. Backward integration of the orbits of the 60 proposed asteroid pairs has shown that they each have had recent (< 1 Myr), low-velocity encounters at distances smaller than the Hill Sphere of the larger of the two asteroids [4], suggesting a common parent body, that subsequently experienced YORP-induced rotation fission [5]. We have begun an observational programme to characterize this population compositionally and thermally, to look for compositional similarities and to further understand their dynamical histories. We present our latest results from this programme, which include optical, low-resolution spectroscopy of the asteroids in a number of pairs observed using the 4.2m William Herschel Telescope and the 3.6m New Technology Telescope. We find that the asteroids of unbound pair (7343) Ockeghem - (154634) 2003 XX38 both exhibit very similar S-type spectra, while the asteroids in the unbound pair (1979) Sakharov - (13732) Woodall exhibit V-type spectra. Results for other pairs will be presented at the meeting. [1] Walsh et al., Nature 454, p188. [2] Scheeres, 2007, Icarus 189, p370. [3] Jacobson et al., 2011, Icarus, 214, p 161. [4] Vokrouhlicky et al., 2008, The AJ 136, p280. [5] Pravec et al., 2010, Nature 466, p1085.

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