Probing the Occurrence of Exoplanets and Brown Dwarfs at Wide Orbits, the NaCo Large Programme - Progress Report
Chauvin G. and the NaCo Large Programme for Giant Planets Imaging collaboration
Since the discovery of the TW Hydrae association, hundreds of young, nearby stars have been identified, sharing common kinematics, photometric and spectroscopic properties. These targets offer offer new opportunities for deep imaging searches for giant planets and brown dwarfs. To date, limited surveys have been carried out with specific target selection criteria (age, distance, spectral types). The next step after the first detections of planet mass companions around most favourable targets is a wider statistical analysis of the frequency and properties of low mass companions as a function of stellar mass and orbital separation. In late 2009, we have initiated a coordinated European Large Programme using angular differential imaging with NaCo at VLT. Our aim is to provide a comprehensive and statistically significant study of the occurence of EGP and BD at large (5-500 AU) orbit separation around 200 young, nearby stars never observed to the depth required to detection planetary mass companions. 75% of the initial survey has been executed providing already exciting results. already exciting results. Here we present the selection of targets for our survey, the observing strategy and the detection limits achieved down to the planetary mass regime typically beyond 10 AU. We will show some preliminary detections as well as our strategy to identify false alarms and characterize true companions. Finally, we will discuss the constraints our survey will provide on the physical properties and the frequency of planetary mass companions at large separation as a test of planet formation theory. Of particular interest, detections from our (young) survey sample will probe evolutionary models of planetary mass companions as a function of age, testing whether predictions of their luminosity and temperature are consistent with the observations. We conclude with the promise of this survey to help prepare for the future generation of deep imaging instruments.