Skip to main content
Article thumbnail
Location of Repository

First Clear Signature of an Extended Dark Matter Halo in the Draco Dwarf Spheroidal

By J. T. Kleyna, M. I. Wilkinson, N. W. Evans and G. F. Gilmore


We present the first clear evidence for an extended dark matter halo in the Draco dwarf spheroidal galaxy based on a sample of new radial velocities for 159 giant stars out to large projected radii. Using a two-parameter family of halo models spanning a range of density profiles and velocity anisotropies, we are able to rule out (at about the 2.5 σ confidence level) halos in which mass follows light. The data strongly favor models in which the dark matter is significantly more extended than the visible dwarf. However, halos with harmonic cores larger than the light distribution are also excluded. When combined with existing measurements of the proper motion of Draco, our data strongly suggest that Draco has not been tidally truncated within ~1 kpc. We also show that the rising velocity dispersion at large radii represents a serious problem for modified gravity (MOND)

Publisher: American Astronomical Society, IOP Publishing
Year: 2001
DOI identifier: 10.1086/338603
OAI identifier:

Suggested articles


  1. (1981). Galactic Dynamics, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.