Galaxy Bullying Caught in the Act
Caroline Foster
Australian Astronomical Observatory

The Ultra-deep images of the Umbrella Galaxy (NGC 4651) have revealed a dramatic system of stellar streams and shells. Using bright tracers such as globular clusters and planetary nebulae around NGC 4651, we are able to measure the motions of the impossibly faint streams in this system, a feat previously only possible for Local Group streams. The Umbrella Galaxy is now the farthest faint stellar stream with known dynamics. With the help of single-orbit modelling and rescaled N-body simulations, we conclude that the umbrella is made of shredded stars from a “bullied” dwarf elliptical galaxy. We point out several lines of evidence suggesting that the Umbrella system is a remarkable analogue to the Sagittarius stream around our own Milky Way!

Date:	Lundi, 16 décembre 2013
Time:	13:00
Where:	Bishop's University
	Jasper Hume Nicolls Building, conference room 1
Contact:	Lorne Nelson