ASTRONOMY: Galactic halo springs surprise

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Astronomers have been left perplexed by observations of a dark matter "halo" around another galaxy that has deepened one of the universe's biggest mysteries.

Astronomers have recently detected substantial haloes of dark matter around galaxies, which signify their presence by the gravitational effect they have on visible stars and gas embedded within them. But a study of one of these haloes yielded a surprise, according to a report in the science journal Nature. A team of researchers at the Space and Environment Technology Center, Los Angeles, found that the spectra, or light wavelengths, of near-infrared emissions from the halo indicated "a very peculiar spectral energy distribution, which cannot be explained by any current models of stellar populations". The halo appeared to be populated with relatively young stars as well as a large number of low-mass stars - the opposite of what would have been expected.