Issue |
A&A
Volume 523, November-December 2010
|
|
---|---|---|
Article Number | A94 | |
Number of page(s) | 19 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/201015074 | |
Published online | 18 November 2010 |
Physical properties of the ESA Rosetta target asteroid (21) Lutetia
II. Shape and flyby geometry⋆,⋆⋆
1
LESIA, Observatoire de Paris
, 5 place Jules Janssen,
92190
Meudon,
France
e-mail: benoit.carry@obspm.fr
2
Université Paris 7 Denis-Diderot, 5 rue Thomas Mann, 75205
Paris Cedex,
France
3
Tampere University of Technology, PO Box 553, 33101
Tampere,
Finland
4
Southwest Research Institute, 1050 Walnut St. #300, Boulder, CO
80302,
USA
5
Starfire Optical Range, Directed Energy Directorate, Air Force
Research Laboratory, Kirtland
AFB, NM
87117-577,
USA
6
W.M. Keck Observatory, 65-1120 Mamalahoa Highway, Kamuela, HI
96743,
USA
7
Johns Hopkins University Applied Physics Laboratory,
Laurel,
MD
20723-6099,
USA
8
European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001,
Santiago de Chile,
Chile
9
IMCCE, Observatoire de Paris, 14 bvd de l’Observatoire,
75014
Paris,
France
10
Gemini Observatory, Northern Operations Center, 670 N. A’ohoku
Place, Hilo,
HI, 96720, USA
11 INAF, Osservatorio Astronomico di Roma, via Frascati 33,
00040 Monteporzio Catone (Roma), Italy
12
Dipartimento di Fisica, Università di Roma Tor
Vergata, via della Ricerca
Scientifica 1, 00133
Roma,
Italy
13
Les Engarouines Observatory, 84570
Mallemort-du-Comtat,
France
14
Geneva Observatory, 1290
Sauverny,
Switzerland
15
Astronomical Observatory, Adam Mickiewicz University,
Sloneczna 36,
60-286
Poznan,
Poland
16
Blauvac Observatory, 84570
St-Estève,
France
17
Observatorio Montcabre, C/Jaume Balmes 24, 08348 Cabrils, Barcelona, Spain
18
Le Cres Observatory, 2 rue des Écoles, 34920 le
Cres,
France
19
Wiggins Observatory, 472 Country Club, Tooele
Utah
84074,
USA
Received: 28 May 2010
Accepted: 26 August 2010
Aims. We determine the physical properties (spin state and shape) of asteroid (21) Lutetia, target of the International Rosetta Mission of the European Space Agency, to help in preparing for observations during the flyby on 2010 July 10 by predicting the orientation of Lutetia as seen from Rosetta.
Methods. We use our novel KOALA inversion algorithm to determine the physical properties of asteroids from a combination of optical lightcurves, disk-resolved images, and stellar occultations, although the last are not available for (21) Lutetia.
Results. We find the spin axis of (21) Lutetia to lie within 5° of (λ = 52°, β = − 6°) in the Ecliptic J2000 reference frame (equatorial α = 52°, δ = + 12°), and determine an improved sidereal period of 8.168270 ± 0.000001 h. This pole solution implies that the southern hemisphere of Lutetia will be in “seasonal” shadow at the time of the flyby. The apparent cross-section of Lutetia is triangular when seen “pole-on” and more rectangular “equator-on”. The best-fit model suggests there are several concavities. The largest of these is close to the north pole and may be associated with strong impacts.
Key words: minor planets, asteroids: individual: (21) Lutetia / methods: observational / techniques: high angular resolution / instrumentation: adaptive optics
Based on observations collected at the W. M. Keck Observatory and at European Southern Observatory Very Large Telescope (program ID:079.C-0493, PI: E. Dotto). The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
Tables 1, 2, 4 and Figs. 3–5 are only available in electronic form at http://www.aanda.org
© ESO, 2010
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