Astronomy Colloquium: Guillaume Thomas (Herzberg/NRC)

Date: Thu. October 11th, 2018, 3:00 pm-4:00 pm

CFIS-u : a blue sky for the stellar halo

Guillaume Thomas (Herzberg/NRC)

The stellar halo of the Milky Way is an incredible source of information, whether about the formation and the evolution of our Galaxy or to trace the Galactic potential in three dimensions. Indeed, the stellar halo is largely populated by the old metal-poor stars originally lying in satellites galaxies or globular clusters that have being disrupted by tidal effects. The spatial distribution of the different populations of the stellar halo allow us to reconstruct the formation history of the Milky Way, and with the advent of the Gaia DR 2, we can also use the kinematics of these stars to trace the Galactic potential at large radius.

I will present the recent result obtained with the Canada France Imaging Survey (CFIS), an ongoing CFHT Large Program that will map 10,000 deg^2 of the northern sky in the u-band to a depth 2.7 mag greater than SDSS and describe why the information added by the u-band is extremely valuable in the study of the stellar halo. With this survey, it has already been possible to trace the profile of the halo up to 220 kpc with the Blue Horizontal Branch (BHB) stars or to trace the stellar disk at an high elevation (z ~8 kpc), possible consequence of the last passage of the Sgr dSph through the Galactic disk.