Research NewsAstronomy

Galactic Disk Contains No Dark Matter

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Science  14 Nov 1997:
Vol. 278, Issue 5341, pp. 1230
DOI: 10.1126/science.278.5341.1230

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Summary

By studying the movement of stars in the disk of our Milky Way galaxy, two teams of French astronomers have concluded that what you see is what you get: The mass of the visible stars appears to account for all the material in the galactic disk. These findings, derived from data gathered by the European astrometric satellite Hipparcos, imply that the main body of our galaxy contains no "dark matter"--invisible material that astronomers believe accounts for up to 90% of the mass of the universe. Instead, both groups argue, the dark matter must be lurking in the galactic halo, a large, spherical region encircling the galaxy containing dust, gas, and globular clusters of very old stars.