Vast Structure of Satellite Galaxies Discovered: Do the Milky Way’s Companions Spell Trouble for Dark Matter?
ScienceDaily (Apr. 25, 2012) — Astronomers from the University of Bonn in Germany have discovered a vast structure of satellite galaxies and clusters of stars surrounding our Galaxy, stretching out across a million light years. The work challenges the existence of dark matter, part of the standard model for the evolution of the universe.
PhD student and lead author Marcel Pawlowski reports the team’s findings in a paper in the journal Monthly Notices of the Royal Astronomical Society.
The Milky Way, the galaxy we live in, consists of around three hundred thousand million stars as well as large amounts of gas and dust arranged with arms in a flat disk that wind out from a central bar. The diameter of the main part of the Milky Way is about 100,000 light years, meaning that a beam of light takes 100,000 years to travel across it. A number of smaller satellite galaxies and spherical clusters of stars (so-called globular clusters) orbit at various distances from the main Galaxy.
Image Info: The galaxy pair UGC 9618 / VV 340, two spiral galaxies at the beginning of a collision. (Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University))