Pan-STARRS1 Data and the Monoceros Ring

Wednesday, 03 December 2014 8 a.m. — 9 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
ERIC MORGANSON (Smithsonian Observatory (Harvard-Smithsonian Center for Astrophysics) and Gemini South Visiting Astronomer)

The Milky Way is surrounded by a giant ring of stars. At least that is our best guess after seeing a huge, contiguous overdensity of stars along many different lines of sight 15-20 kpc away from the Galactic center stretching 4 kpc away from the plane in either direction.  Dubbed "the Monoceros Ring," this formation is a major mystery of outer Milky Way structure. Is it a "natural" part of the Milky Way, a flare or warping of the disk? Or is it the result of a recent merger? If so, is it composed of stars pulled out of our thin disk or from a tidally disrupted neighbor? Answering these questions has been hindered by a lack of contiguous optical data in the plane of the Milky Way. But no more! Pan-STARRS1 is the first optical survey with sufficient depth to probe down to 4 degrees (0.5 kpc) within the plane of the Milky Way over most (75%) of the plane. We use this data to make the first large scale, contiguous, quantitative map of the outer Milky and particularly the Monoceros Ring. These maps immediately provide significant insight into the nature of the Monoceros Ring, and we are hopeful that more analytic modelling will allow us to solve this Galactic mystery.