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Titre du document / Document title

Shape, size and multiplicity of main-belt asteroids. I. Keck Adaptive Optics survey

Auteur(s) / Author(s)

MARCHIS F. (1) ; KAASALAINEN M. (2) ; HOM E. F. Y. (3) ; BERTHIER J. (4) ; ENRIQUEZ J. (1) ; HESTROFFER D. (4) ; LE MIGNANT D. (5) ; DE PATER I. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Astronomy, University of California, 601 Campbell Hall, Berkeley, CA 94720-3411, ETATS-UNIS
(2) Department of Mathematics and Statistics, Gustaf Hallstromin katu 2b, P.O. Box 68, University of Helsinki, 00014, FINLANDE
(3) Graduate Group in Biophysics, University of California-San Francisco, Genentech Hall, 600, 16th Street, San Francisco, CA 94143-2240, ETATS-UNIS
(4) IMCCE, UMR-CNRS 8028, Observatoire de Paris, 77 Av. Denfert Rochereau, 75014 Paris, FRANCE
(5) W.M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743, ETATS-UNIS

Résumé / Abstract

This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (∼5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2-σ detection profile: in average on the data set, a moonlet located at 2/100 x RHill (1/4 x RHill) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D < 200 km, it is underestimated on average by 6-8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450-464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (∼6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to determine a unique photometric mirror pole solution, which is normally ambiguous for asteroids moving close to the plane of the ecliptic (e.g., 192 Nausikaa and 52 Europa). The photometric inversion models agree well with the AO images, thus confirming the validity of both the lightcurve inversion method and the AO image reduction technique.

Revue / Journal Title

Icarus    ISSN  0019-1035   CODEN ICRSA5 

Source / Source

2006, vol. 185, no1, pp. 39-63 [25 page(s) (article)] (2 p.1/4)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, Amsterdam, PAYS-BAS  (1962) (Revue)

Mots-clés anglais / English Keywords

Jupiter satellite

;

Solar system

;

Image processing

;

Data reduction

;

Infrared observation

;

Europa

;

Metis

;

Models

;

Contact binary

;

Light curves

;

Algorithms

;

Deconvolution

;

Modelling

;

Spheres

;

Asteroids

;

Albedo

;

Diameter

;

Adaptive optics

;

Asteroid belt

;

Multiplicity

;

Mots-clés français / French Keywords

Satellite Jupiter

;

Système solaire

;

Traitement image

;

Réduction donnée

;

Observation IR

;

Europa

;

Metis

;

Modèle

;

Binaire contact

;

Courbe lumière

;

Algorithme

;

Déconvolution

;

Modélisation

;

Sphère

;

Astéroïde

;

Albédo

;

Diamètre

;

Optique adaptative

;

Ceinture astéroïdale

;

Multiplicité

;

Mots-clés espagnols / Spanish Keywords

Satélite Jupiter

;

Observación IR

;

Modelo

;

Binario contacto

;

Diámetro

;

Cintura asteroidal

;

Mots-clés d'auteur / Author Keywords

Asteroids; Infrared observations; Asteroids

;

surfaces; Data reduction techniques; Image processing

;

Localisation / Location

INIST-CNRS, Cote INIST : 10196, 35400015880116.0040

Nº notice refdoc (ud4) : 18214743



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