Star struck: A model of a galaxy, showing stars streams torn from smaller dwarf galaxies. The structures seen in the new survey support this prediction of a complicated outer galaxy for the Milky Way. The region shown is about one million light years across.
Credit: K. Johnston, J. Bullock
Related research, led by Jelte de Jong from the Max Planck Institute for Astronomy in Heidelberg, Germany, was presented at an International Astronomical Union Symposium, in Copenhagen, Denmark in June.
His team used the SEGUE data to examine a stream of stars called the Low Latitude Stream (also known as the Monoceros Ring), which circles the Milky Way just outside the plane of the galactic disk. The stream is thought to be trailing from a dense lump of stars near the constellation Canis Major, which was once a dwarf galaxy.
Crucial constraints
The scientists plotted the relationship between stars’ absolute magnitude, luminosity, classification, and effective temperature. These plots can be used to distinguish between different models of the Low Latitude Stream, and help to shed light on the nature of the system, they say.
The results – also published on the Arxiv physics website – provide “crucial constraints” for theoretical models of the evolution of these star streams, the experts said.
Geraint Lewis an astrophysicist from the University of Sydney in Australia, who was not involved in the survey, said the research represents the “first step in what’s going to come out of the SEGUE survey”.
“It seems a bit weird that we’ve been looking at the Milky Way for 100 years and we still don’t know how the stars are distributed,” he added. “What’s been shown now is that it is not a smooth galaxy; there are lots of lumps and bumps hanging around.”
