Benoit Carry: Astronomer


Welcome to Benoit Carry's web pages

Paris — June 26, 2013

B. Carry Photo

Benoit Carry is a young planetary scientist interested in the study of the Solar System Small Bodies.
He principally uses large ground-based telescopes equipped with adaptive optics cameras, such as the W. M. Keck Observatory or the ESO Very Large Telescope. You will find here some examples of his work.
He is an astronomer at the Institut de mecanique celeste et de calcul des ephemerides (IMCCE), working on the physical properties of asteroids. of the Before, he has been a Research Fellow at the European Space Astronomy Centre (ESAC) of the European Space Agency (ESA), a Research and Teaching Assistant at the University Paris 7 Denis-Diderot, and he did his PhD at the LESIA in the Paris Observatory in 2009, after two years spent within the European Southern Observatory (ESO) in Chili.

Main Research interests

1- Why studying small bodies?

The Small Bodies of our Solar System (asteroids, comets, Centaurs, and Trans-Neptunian Objects) are the remnants of the primary stages of planetary formation. They are the leftovers of the processes that occured during the accretion of the early planetissimal into planets, some 4.5 Gyrs ago.
Contrarily to the planets that have evolved over eons, through e.g., plate tectonic, volcanism, and erosion, most of the small bodies are too small to possess enough internal energy to evolve. They are therefore pristine material, directly delivered from the early Solar System.
By understanding their composition (mineralogy) and dynamic, we have access to strong constraints on the distribution of elements in the primordial nebulae where the Earth was born.

2- The density as a strong indicator of composition

I study the physical properties (spin, size, and shape) of main-belt asteroids. The main goal is to obtain their density (using mass estimates determined elsewhere), which is perhaps the most fundamental properties to understand their composition and internal structure.

I use for that disk-resolved images of these asteroids, obtained with the largest telescopes on Earth like the W. M. Keck on Hawaii, or the ESO Very Large Telescope in Chile. I am an active member of the Resolved Asteroid Program.

In collaboration with Mikko Kaasalainen and Josef Durech, we are developping a multi-data 3-D shape-reconstruction algorithm called Knitted Occultation, Adaptive-optics, and Lightcurve Analysis (KOALA). This algorithm allows the combined inversion of three kind of observations: chords from stellar occultations, contours from disk-resolved images, and photometry from optical lightcurves. Current development aims at allowing more diverse data sets to be included in the KOALA: e.g., thermal radiometry, visibilities from interferometry.

You can see some examples of my work here: on the dwarf-planet (1) Ceres, the large asteroid (2) Pallas, or the asteroid (21) Lutetia, target of the ESA Rosetta mission.

3- The binaries out there

In parallel with the study of the physical properties, I am also interested in the multiplicity of minor planets. Indeed, the mutual orbits of an asteroid and its moon yields the total mass of the system, which, coupled with the volume (see above), provides the density.

I am therefore involved in two programs using large ground-based adaptive-optics equipped telescopes. With the Resolved Asteroid Program, we mostly concentrate on main-belt asteroids, while with the Trans-Neptunian Binary (TNB) Team (J. Berthier, A. Doressoundiram, D. Hestroffer, C. Nitschelm, F. Vachier, O. Vaduvescu), we concentrate on binary systems in the Centaurs and Kuiper belt regions.

Lastest news

Ground-based observations support Rosetta flyby

Pasadena, USA — Friday, 8 October 2010


We have used the large ground-based telescopes, equipped with adaptive optics and our recent KOALA algorithm, to accurately predict the size and shape of the asteroid (21) Lutetia at 200 million km from Earth.

The 3D shape model we derived has been convincingly validated by the high resolution images returned by the ESA Rosetta spacecraft. Our ground-based observations correctly predicted both the size and shape of the asteroid to within a few percent! This demonstrates that the combination of large Earth-based telescopes, adaptive optics technology and our KOALA algorithm is a powerful way to study asteroids.

See the full press release here, as well as the announcement at ESO.

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Author: Benoit Carry, Last modification: 2013 Jun 26