Physical characterization of double asteroid (617) Patroclus from 2007/2012 mutual events observations

J. Berthier, P. Descamps, F. Vachier, J. Normand, L. Maquet, F. Deleflie, F. Colas, A. Klotz, J-P Teng-Chuen-Yu, A. Peyrot, F. Braga-Ribas, F. Marchis, A. Leroy, S. Bouley, G. Dubos, J. Pollock, T. Pauwels, P. Vingerhoets, J. A. Farrell, P., V SadaV Reddy, K. Archer, H. H. Hamanowa

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Abstract

We publish a set of 16 light curves of mutual events inside the synchronous system of the Jupiter Trojan (617) Patroclus. Patroclus is th only binary system of the six target asteroids of the forthcoming NASA Discovery-class mission Lucy. Determining the physical parameters of the system is therefore of primary importance in helping to plan the flyby mission. Light curves were acquired during two follow-up campaigns of 6 months each between January–June 2007 and July–December 2012. Eight small eclipse events of amplitude of 0.2–0.3 mag were recorded in 2007. On the other hand, in 2012, the amplitudes of the phenomena were much deeper, between 0.6 and 0.8 mag, due to a nearly edge-on configuration of the system. We refined the sidereal period to 102.78624 ± 0.00015h = 4.282760 ± 0.000005days. The J2000 ecliptic coordinates of the pole of the system were found to be λ = 235.3 ± 1.2° andβ = − 62.4 ± 0.2°. The volume ratio was determined equal to q = 0.69 ± 0.08. By using a model of inhomogeneous Roche ellipsoids in hydrostatic equilibrium, we derived a bulk density of 0.81 ± 0.16g/cm3 and a surface grain density of 2.69 ± 0.36g/cm3 in agreement with spectroscopic observations of this P-type asteroid. As a validation, our solution was applied to revisit recent results obtained from observations of another type: AO astrometry and stellar occultation. Our model is thus perfectly able to account for these observations after fitting the mutual separation to the value of 695 ± 10km. Consequently, the area-equivalent diameter of the system as a whole is derived DΑ = 168.8 ± 2.6km.
Original languageEnglish
Article number113990
JournalIcarus
Volume352
DOIs
Publication statusPublished - Dec 2020

Bibliographical note

Funding Information:
F.B-R acknowledges the CNPq grants 309578/2017-5 and Coordenac?a?o de Aperfeic?oamento de Pessoal de Ni?vel Superior - Brasil (CAPES) - Finance Code 001. Part of the results is based on observations taken at Pico dos Dias Observatory of the National Laboratory of Astrophysics (LNA/Brazil).

Funding Information:
F.B-R acknowledges the CNPq grants 309578/2017-5 and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 . Part of the results is based on observations taken at Pico dos Dias Observatory of the National Laboratory of Astrophysics (LNA/Brazil).

Publisher Copyright:
© 2020 Elsevier Inc.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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