Near-infrared mapping and physical properties of the dwarf-planet Ceres

Carry, B.; Dumas, Christophe; Fulchignoni, M.; Merline, W. J.; Berthier, J.; Hestroffer, Daniel; Fusco, Thierry; Tamblyn, Peter

doi:10.1051/0004-6361:20078166

Cited by 104 publications

(126 citation statements)

References 47 publications

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“…We first extracted the contour of (21) Lutetia on each image using a Laplacian of Gaussian wavelet (see Carry et al 2008, for more detail about this method). These contours provide a direct measurement of Lutetia's size and shape at each epoch (Table 1).…”

Section: The Koala Methodsmentioning

confidence: 99%

“…In this respect, our observing program with adaptive optics, allowing diffraction-limited observations from the ground with 10 m-class telescopes, has now broken the barrier that separated asteroids from real planetary worlds (e.g., Conrad et al 2007;Carry et al 2008;Drummond et al 2009;Carry et al 2010;Drummond et al 2010). Their shapes, topography, sizes, spins, surface features, albedos, and color variations can now be directly observed from the ground.…”

Section: Introductionmentioning

confidence: 99%

“…We reduced the data using usual procedures for near-infrared images, including bad pixel removal, sky subtraction, and flatfielding (see Carry et al 2008, for a more detailed description). No effort has been made to restore photometric accuracy over the apparent disk and some ringing effects can be seen in the frames.…”

Section: Disk-resolved Imaging Observationsmentioning

confidence: 99%

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Physical properties of the ESA Rosetta target asteroid (21) Lutetia

Carry

Kaasalainen

Leyrat

et al. 2010

A&A

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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 8.168 270±0.000 001 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.

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Section: The Koala Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Physical properties of the ESA Rosetta target asteroid (21) Lutetia

Carry

Kaasalainen

Leyrat

et al. 2010

A&A

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“…The most accurate values for the diameter of (1) Ceres come from HST observations (Thomas et al 2005) and adaptive optics (AO) observations using the Keck II telescope (Carry et al 2008). The HST observations led to an oblate spheroid with axes of a = b = 487.3 km and c = 454.7 km, resulting in an effective diameter of 2 × (a × b × c) 1/3 = 952.4 km.…”

Section: Diameter and Albedo Calculationsmentioning

confidence: 99%

Catalogue of ISO LWS observations of asteroids

Hormuth

Müller

2009

A&A

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Context. The long wavelength spectrometer (LWS) onboard the infrared space observatory (ISO) observed the four large main-belt asteroids (1) Ceres, (2) Pallas, (4) Vesta, and (10) Hygiea multiple times. The photometric and spectroscopic data cover the wavelength range between 43 and 197 μm, and are a unique dataset for future investigations and detailed characterisations of these bodies. Aims. The standard ISO archive products, produced through the last post-mission LWS pipeline, were still affected by instrument artefacts. Our goal was to provide the best possible data products to exploit the full scientific potential of these observations. Methods. For all asteroid observations we analysed in detail the dark current, the calibration reference flashes, the space environment effects (glitches), memory effects, tracking influences, and various other sources of uncertainty. We performed a refined reduction of all measurements, corrected for the various effects, and re-calibrated the data. We outline the data reduction process and give an overview of the available data and the quality of the observations. We apply a thermophysical model to the flux measurements to derive far-IR based diameter and albedo values of the asteroids. The measured thermal rotational lightcurve of (4) Vesta is compared to model predictions. Results. The catalogue of LWS (long wavelength spectrometer) observations of asteroids contains 57 manually reduced datasets, including seven non-standard observations, which as such did not have final pipeline products available before. In total, the archive now contains 11 spectral scans and 46 fixed grating measurements with a simultaneous observation at 10 key wavelengths distributed over the full LWS range. The new data products are now accessible via the ISO data archive as highly processed data products (HPDP).Conclusions. The quality of the data products was checked against state-of-the-art thermophysical model predictions and an excellent agreement was found. The absolute photometric accuracy is better than 10%. The calibrated spectra will serve as a source for future mineralogical studies of dwarf planets and dwarf planet candidates.

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“…Despite the rough assumptions of our model it may fit the dwarf-planet Ceres, whose shape is well described by an oblate spheroid to the limit of measurement, or to a lesser extent to the asteroid 16 Psyche or even to 4 Vesta (Thomas et al 2005;Drummond & Christou 2008;Carry et al 2008), all of them orbiting the sun with relatively low eccentricities. Besides, the perturbation of the torque-free motion is of the order of 10 −7 for Ceres and 4 Vesta -targets of actual interest since the approval of the NASA Dawn mission (Russell et al 2003) -and less than that for 16 Psyche.…”

Section: Introductionmentioning

confidence: 99%

First-order rotation solution of an oblate rigid body under the torque of a perturber in circular orbit

Lara

Fukushima

Ferrer

2010

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Aims. We discuss the rotational motion of an axisymmetric rigid body under the torque exerted by a massive point orbiting in a circular Keplerian orbit. The perturbation of the torque-free motion is modelled by applying MacCullagh's approximation. Methods. Through successive approximations we use the unperturbed motion solution to get a first order solution for the Hamilton equations, which we apply to the complete problem.Results. The solution of the perturbed problem is computed in closed form without the usual series expansions, and shows the main effects on the dynamics of the rigid body that are introduced by the perturbation. Remarkably, special configurations are discovered, for which the perturbation only introduces periodic oscillations in the torque-free motion. An application to the dwarf-planet Ceres shows the reliability of the analytical solution.

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Near-infrared mapping and physical properties of the dwarf-planet Ceres

Cited by 104 publications

References 47 publications

Physical properties of the ESA Rosetta target asteroid (21) Lutetia

Physical properties of the ESA Rosetta target asteroid (21) Lutetia

Catalogue of ISO LWS observations of asteroids

First-order rotation solution of an oblate rigid body under the torque of a perturber in circular orbit

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