By Ron Cowen
Spacecraft observations indicate that a vast, unseen halo of hot gas envelops our home galaxy. Large enough that it literally could be brushing up against the Milky Way’s nearest galactic neighbors, the halo may be the remnants of the primordial material that built the Milky Way, researchers reported this week.
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Kenneth R. Sembach of the Space Telescope Science Institute in Baltimore and his colleagues base their findings on observations of gas clouds known to be raining down on our galaxy (SN: 1/25/97, p. 55). His team examined 60 clouds at far-ultraviolet wavelengths, which for the first time, revealed the clouds’ hot, outer edges.