Archaeology of Extrasolar Terrestrial Planetary Systems
We now stand firmly in the era of solid exoplanet detection via
Kepler and other state of the art facilities. Yet the empirical
characterization of these most intriguing planets is extremely
challenging. Transit plus radial velocity data can yield planet
mass and radius, and hence planet density, but the bulk composition
remains degenerate and model?dependent. The abundances of a handful
of exoplanet atmospheres can be estimated from transit spectroscopy, but
probing only the tenuous outer layers of those planets.
Fortunately, as demonstrated by Spitzer and complementary ground?based
observations, debris disk?polluted white dwarfs can yield highly
accurate information on the mass and chemical structure of rocky minor
planets (i.e. exo?asteroids), the building blocks of solid exoplanets.
The white dwarf distills the planetary fragments, and provides powerful
insight into elemental composition of the parent body. This
archaeological method provides empirical data on the assembly and
chemistry of exo-terrestrial planets that is unavailable for any
planetary system orbiting a main?sequence star. In the Solar System, the
asteroids (or minor planets) are leftover building blocks of the
terrestrial planets, and we obtain their compositions -- and hence that
of the terrestrial planets -- by studying meteorites. Similarly, one can
infer the composition of exo-terrestrial planets by studying tidally
destroyed and accreted asteroids at polluted white dwarfs.
I will present ongoing, state of the art results using this
unconventional technique, emphasizing the lasting impact of infrared
space missions like Spitzer. Some highlights will include the recent
detection of terrestrial-like debris in the Hyades star cluster, as well
as the detection of a few water-rich planetesimals that may represent
the building blocks of habitable exoplanets.
|Date: ||Jeudi, le 25 avril 2013|
|Lieu: ||Université de Montréal|
| ||Pavillon Roger-Gaudry, local D-460|
|Contact: ||Patrick Dufour|