Astronomers are puzzled why it appears that some of the most distant galaxies in the universe are more dense with stars than expected. In this image of the Milky Way star cluster Omega Centauri, bright stars have been coloured blue, faint ones red. For more distant galaxies, though, faint stars are impossible to see. Now it turns out some of the most distant galaxies in the universe are more packed with stars than astronomers expected.
The data galaxies give astronomers comes from the light of their stars. But stars don't carry all of a galaxy's mass. According to the current model, some of the mass is invisible dark matter, which can't be measured directly.
"To estimate exactly what is the mass that they have, we always use this conversion factor, to convert light into mass," says University of Oxford astronomer Michele Cappellari. "The conversion we used for many decades was wrong, and will have to be revised," Cappellari said.
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