Physical and dynamical characterisation of the unbound asteroid pair 7343-154634

Duddy, S.R. and Lowry, S.C. and Wolters, S.D. and Christou, A. and Weissman, P. and Green, S.F. and Rozitis, B. (2012) Physical and dynamical characterisation of the unbound asteroid pair 7343-154634. Astronomy and Astrophysics, 539 . (A36) 1-11. ISSN 0004-6361. E-ISSN 1432-0746. (doi:https://doi.org/10.1051/0004-6361/201118302) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1051/0004-6361/201118302

Abstract

Context. Models have shown that asteroids can undergo fission if their rate of rotation is steadily increased. The forces acting to pull the asteroid apart exceed the material strength and gravitational force holding the asteroid together and material can escape from the surface of the asteroid. Initially forming a binary asteroid system, the components are capable of decoupling at low relative velocity from their mutual orbit if their mass ratio is less than 0.2. A number of asteroids with very similar orbital elements have been shown to have had very recent (<1 Myr) encounters at distances smaller than the Hill sphere radius of the larger of the asteroids. The mass ratio of the asteroids in each pair is estimated to be less than 0.2, suggesting that these unbound pairs are the result of rotational fission. Aims. We determine whether the asteroids in one such unbound pair, (7343) Ockeghem and (154 634) 2003 XX28, share a common composition, indicative of asteroids formed from a common parent and further constrain a likely formation age for this pair. Methods. We have obtained spectroscopic observations of each asteroid covering the wavelength range 0.45 to 1.0 microns. Using thermal observations we have measured the size and albedo of (7343) Ockeghem. Combined with optical lightcurve data of both asteroids, we have constrained the size and density of the asteroids and estimated the strength of the Yarkovsky force experienced by both. This improved physical information has been used in new dynamical simulations of the asteroids' orbits to better constrain a formation time of this pair. Results. We find that the asteroids have very similar spectra consistent with an S-type taxonomy. The geometric albedo of (7343) Ockeghem, 0.20 ± 0.06 is consistent with this classification. The mass ratio range of the asteroids assuming an equal density, 0.007 to 0.065, is consistent with models of unbound asteroid pair formation. A new dynamical analysis has indicated that an absolute lower limit for the age of this pair is 400 kyr with a more likely age around 560 kyr, lower than a previous estimate of 800 kyr. © 2012 ESO.

Item Type: Article
Additional information: Unmapped bibliographic data: C7 - A36 [EPrints field already has value set] LA - English [Field not mapped to EPrints] J2 - Astron. Astrophys. [Field not mapped to EPrints] AD - Centre for Astrophysics and Planetary Science, University of Kent, Canterbury, Kent, CT2 7NH, United Kingdom [Field not mapped to EPrints] AD - Planetary and Space Sciences, Department of Physical Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom [Field not mapped to EPrints] AD - Planetary Science Section, Jet Propulsion Laboratory, Pasadena, CA 91109, United States [Field not mapped to EPrints] AD - Armagh Observatory, College Hill, Armagh, BT61 9DG, United Kingdom [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: asteroids: general, Minor planets, Asteroid pairs, Binary asteroids, Dynamical analysis, Dynamical simulation, Gravitational forces, Lower limits, Mass ratio, Material strength, Minor planets, Orbital element, Physical information, Relative velocity, Wavelength ranges, Solar radiation, Spheres, Strength of materials, Asteroids
Subjects: Q Science > QB Astronomy
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Stephen Lowry
Date Deposited: 08 Dec 2015 22:22 UTC
Last Modified: 21 Dec 2015 14:55 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/52282 (The current URI for this page, for reference purposes)
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