case western reserve university



Flared outer disk or Ring around the Galaxy?

Heather Morrison (Case Western Reserve University)

I will present recent spectroscopy from a multi-faceted study of the Milky Way halo (the Spaghetti survey). Our results call into question the identification of structures toward the edge of the Milky Way disk (eg Monceros; the Ring around the Galaxy) with debris from accretions of dwarf satellites. Our velocity data (and that of Yanny et al 2003) show that these detections are consistent with a simpler explanation: a flared outer disk caused by interaction with a still undiscovered dwarf which heated the outer disk.