8-12 juin, 2014


BANYAN: Searching for young stars in the Solar neighborhood

Lison Malo (CFHT & Université de Montréal)

René Doyon, David Lafrenière, Étienne Artigau, Jonathan Gagné, Loic Albert, (Université de Montréal)

We present a new method based on a Bayesian analysis to identify new members of nearby young kinematic groups (BANYAN; Malo et al. 2013). The analysis minimally takes into account the position, proper motion, magnitude and color of a star, but other observables can be readily added if desired (e.g. radial velocity, distance). It returns a probability of the star being member of a given group together with a most likely distance and radial velocity. When applied to known members, the statistical distances and radial velocities agree with the measured values within 10% and 1.9 km/s, respectively. We use this method to find new young low-mass stars in the beta Pictoris (BPMG) and AB Doradus moving groups and in the Tuc-Hor, Columba, Carina and Argus associations (10-120 Myr). Starting from a sample of 920 K5V-M5V stars showing youth indicators such as Halpha and X-ray emission, our analysis yields more than 200 new highly probable low-mass members of the kinematic groups analyzed. To confirm membership and youth, we have initiated follow-up spectroscopic observations to measure their radial velocity (predicted by our analysis) and verify various age indicators (such as lithium equivalent width, stellar rotation, bolometric luminosity, effective temperature). So far, we have secured the radial velocity for 130 candidate members (Malo et al. accepted in ApJ) and we have estimated the Bolometric luminosity and effective temperature for 49 stars using ESPaDOnS on CFHT (Malo et al. submitted). Combining these fundamental parameters to the Dartmouth Magnetic evolutionary models, we find that, in general, low-mass stars in the BPMG need more than 2.5 kG magnetic field strength to reproduce the bolometric luminosity and inflated radii in an age range of 20-30 Myr. In this talk, we will briefly review the last ten years of research to identify new members of young moving groups and show how our new statistical method combined to SPIRou on CFHT and the Gaia mission will help the community to establish stars as new members of nearby young kinematic groups.
(doit être confirmé par le SOC)