Dr. Franck Marchis

January 2, 2008 Franck Marchis

SETI Institute Principal Investigator

Dr. Franck Marchis is a Principal Investigator at the Carl Sagan Center of the SETI Institute, and also Assistant Research Astronomer at the University of California at Berkeley.

Our solar system is characterized by considerable diversity of its constituent bodies. Franck Marchis’ first involvement in the study of this diversity started in 1996 while working at the UNAM Astronomy Department in Mexico City.  He made the first ground-based observations of the volcanoes on the jovian moon Io, using the first Adaptive Optics (AO) systems available on the European Southern Observatory (ESO) 3.6 m telescope at Chile’s La Silla Observatory. After a brief stay in London and four years in Chile at ESO, he completed in 2000 his PhD in France. This doctoral research described the application of adaptive optics to the study of the solar system.

He continued this explorative work at U. C. Berkeley where he had the opportunity to use the Keck 10 m telescope and its revolutionary Laser Guide Star AO system. In collaborations with astronomers of the Observatoire de Paris, he searched for, and studied moons around asteroids. In 2005, this team discovered the first triple asteroidal system composed of Sylvia, a 200-km size irregular asteroid, surrounded by two kilometer-size satellites named Romulus and Remus. The existence of multiple asteroid systems provides direct clues about the collisional past of the solar system and the formation of major planets. The direct measurement of the bulk density of an asteroid available when the moon’s orbit is well constrained give indications about the composition and distribution of material in the asteroid.

Franck is also involved in the definition of new generation of AOs for 8 - 10 m class telescopes and data processing of images, both astronomical and biological, using fluorescence microscopy. His research involves both undergraduate and graduate students, and Marchis is eager about contributing to the diversity of our science community and educating a new generation of researchers.



Size, Shape, and Multiplicity in the Jupiter-Trojan population

The jovian Trojan asteroids are quite possibly the most primitive (least collisionally evolved) SolarSystem bodies easily accessible by observations. We propose a multi-instrument campaign to ex-plore the fundamental properties (size, shape, visible albedo, and internal structure) of these objectsusing the capabilities of the Spitzer telescope, several middle size ground-based telescopes, and thehigh angular resolution LGS Keck AO system. Spitzer’s Infrared Spectrograph (IRS) is providingthe best FIR data set, which will be complemented by nearly simultaneous rotational lightcurveobservations in reflected sunlight. We will then constrain the bulk properties of the asteroids us-ing detailed thermal models , which require the combination of visible and thermal infrared data.Our study will be performed in coordination with a network of mid-sized ground-based telescopes(Lick- 3m, Lick-1m, Pic du Midi-1m, OHP-1m) in the optical to characterize the shape and visiblealbedo. Additionally, we have started a high angular resolution study of Trojans aimed at lookingfor binary systems. We are taking advantage of the spectacular high angular resolution provided bythe Keck LGS AO system on faint targets (75 mas on 15-17.5th magnitude). This ambitious program combines data from several facilities to obtain direct insights on the inter-nal structure, surface properties, and formation of Trojan asteroids, it will increase significantly ourknowledge about minor bodies in the Solar System.

Franck Marchis Website at U.C. Berkeley