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From left: Dennis Zaritsky, intensity map of hydrogen absorption in Milky Way halo (galactic coordinates), Huanian Zhang.

Neutral Hydrogen Permeating the Milky Way Halo

After combining hundreds of thousands of spectra of extragalactic objects, Steward Postdoc Huanian Zhang and Professor Dennis Zaritsky report the first detection of diffuse hydrogen wafting about in a vast halo surrounding the Milky Way. Such a halo had been postulated based on what astronomers knew about other galaxies, but never directly observed. The map of the H-alpha absorption across the areas of sky that were studied show a low, but consistent, level of absorption of light by hydrogen. You can read the UA press release HERE, and a WIRED UK article HERE. The preprint can be found HERE

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