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The Resolved Asteroid Program – Size, shape, and pole of (52) Europa

Merline, W.J. and Drummond, J.D. and Carry, B. and Conrad, A. and Tamblyn, P.M. and Dumas, C. and Kaasalainen, M. and Erikson, A. and Mottola, S. and Ďurech, J. and Rousseau, G. and Behrend, R. and Casalnuovo, G.B. and Chinaglia, B. and Christou, J.C. and Chapman, C.R. and Neyman, C. (2013) The Resolved Asteroid Program – Size, shape, and pole of (52) Europa. Icarus: International Journal of Solar System Studies, 225 (1), pp. 794-805. Elsevier. doi: 10.1016/j.icarus.2013.01.010. ISSN 0019-1035.

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Official URL: http://dx.doi.org/10.1016/j.icarus.2013.01.010


With the adaptive optics (AO) system on the 10 m Keck-II telescope, we acquired a high quality set of 84 images at 14 epochs of asteroid (52) Europa on 2005 January 20, when it was near opposition. The epochs covered its 5.63 h rotation period and, by following its changing shape and orientation on the plane of sky, we obtained its triaxial ellipsoid dimensions and spin pole location. An independent determination from images at three epochs obtained in 2007 is in good agreement with these results. By combining these two data sets, along with a single epoch data set obtained in 2003, we have derived a global fit for (52) Europa of diameters a  b  c = (379 x 330 x 249) ± (16 x 8 x 10) km, yielding a volume-equivalent spherical-diameter of (abc)1/3 = 315 +/- 7 km, and a prograde rotational pole within 7deg of [RA;Dec] = [257;+12] in an Equatorial J2000 reference frame (Ecliptic: 255;+35). Using the average of all mass determinations available for (52) Europa, we derive a density of 1.5 ± 0.4 g cm-3, typical of C-type asteroids. Comparing our images with the shape model of Michalowski et al. (2004, Astron. Astrophys. 416, 353), derived from optical lightcurves, illustrates excellent agreement, although several edge features visible in the images are not rendered by the model. We therefore derived a complete 3-D description of (52) Europa’s shape using the KOALA algorithm by combining our 18 AO imaging epochs with 4 stellar occultations and 49 lightcurves. We use this 3-D shape model to assess these departures from ellipsoidal shape. Flat facets (possible giant craters) appear to be less distinct on (52) Europa than on other C-types that have been imaged in detail, (253) Mathilde and (511) Davida. We show that fewer giant craters, or smaller largest-sized craters, is consistent with its expected impact history. Overall, asteroid (52) Europa is still well modeled as a smooth triaxial ellipsoid with dimensions constrained by observations obtained over several apparitions.

Item URL in elib:https://elib.dlr.de/82813/
Document Type:Article
Title:The Resolved Asteroid Program – Size, shape, and pole of (52) Europa
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Merline, W.J.Southwest Research Institute, Boulder, CO, USAUNSPECIFIED
Drummond, J.D.Starfire Optical RangeUNSPECIFIED
Carry, B.Observatoire de ParisUNSPECIFIED
Conrad, A.European Space Astronomy Centre, ESAUNSPECIFIED
Tamblyn, P.M.Southwest Research Institute, Boulder, CO, USAUNSPECIFIED
Kaasalainen, M.Tampere University of TechnologyUNSPECIFIED
Erikson, A.anders.erikson (at) dlr.deUNSPECIFIED
Mottola, S.stefano.mottola (at) dlr.deUNSPECIFIED
Ďurech, J.Charles University in PragueUNSPECIFIED
Rousseau, G.CdR & CdL GroupUNSPECIFIED
Behrend, R.CdR & CdL GroupUNSPECIFIED
Casalnuovo, G.B.CdR & CdL GroupUNSPECIFIED
Chinaglia, B.CdR & CdL GroupUNSPECIFIED
Christou, J.C.Gemini ObservatoryUNSPECIFIED
Chapman, C.R.Southwest Research Institute, Boulder, CO, USAUNSPECIFIED
Neyman, C.Keck ObservatoryUNSPECIFIED
Journal or Publication Title:Icarus: International Journal of Solar System Studies
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1016/j.icarus.2013.01.010
Page Range:pp. 794-805
Keywords:Asteroids Adaptive optics Photometry Occultations
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Vorhaben Asteroiden und Kometen (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Asteroids and Comets
Institute of Planetary Research > Extrasolar Planets and Atmospheres
Deposited By: Mottola, Dr.phys. Stefano
Deposited On:19 Sep 2013 09:28
Last Modified:19 Sep 2013 09:28

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