Welcome: Our small workshop will be held in Grenoble from Monday May 12th at 13h30 to Wednesday 14th at 12h. It  will be targeted at exploring our ability to measure elemental abundances in exoplanets atmospheres, in order to constrain the formation scenario of a given exoplanet. We will first address basics : how did we measured the abundances on Jupiter and other Solar System planets ? And also: what actually is the physic behind abundances shaping absorption lines in exoplanet atmospheres ? How do lines connect to our observed spectra with their limited resolution ? Also, we should keep in mind the main goal of measuring abundances: how does the formation scenario of a planet can influence abundances in its photosphere? We know Solar system giant planets' atmopsheres are enriched with respect to the Sun, but should it be the case for a 4 Jupiter mass planet formed by core accretion? What about the same object formed by gravitational instability ? Of course we will be discussing about our current attempts at measuring abundances in exoplanets atmospheres, by transits, low resolution spectroscopy  or doppler spectroscopy. Finally we should have all the material in mind to launch an open discussion/synthesis about the best instruments and technics that we can use for abundances measurements.

Here is an outline of the program, to be held over 2 days:

• I : Abundances within our Solar System
• II : How does formation scenario influences abundance, or conversely how abundances are a tracer of formation.
• III:  The physics of lines and abundances: from elemental abundances to lines and from lines to spectra.
• IV: Observations: what is currently being done in the realm of atmosphere measurements ? What will we be able to do in the future, and with which instrument.
• V:  Synthesis and Discussion