Astronomer: Dwarf Galaxies Are ‘Eerie’

U.S. astronomers have discovered stars in dwarf spheroidal galaxies behave in a manner suggesting they are dominated by dark matter.

University of Michigan astronomy Professor Mario Mateo and post-doctoral researcher Matthew Walker measured the velocity of 6,804 stars in seven dwarf Milky Way satellite galaxies. They found, contrary to Newton’s law of gravity, stars in those galaxies don’t move slower the farther they are from their galaxy’s core.

These galaxies show a problem right from the center, Mateo said. The velocity doesn’t get smaller. It just stays the same, which is eerie.

The findings more than double the amount of data having to do with such galaxies, the astronomers said, allowing the galaxies to be studied in an unprecedented manner.

Our research shows that dwarf galaxies are utterly dominated by dark matter, so long as Newtonian gravity adequately describes these systems, said Walker.

Dark matter is a substance astronomers haven’t directly observed but deduce its existence because of its gravitational effects on visible matter.

The findings appeared in the Sept. 20 issue of the Astrophysical Journal. Walker is to present a paper on his research Tuesday during the Magellan Science Meeting in Cambridge, Mass.