The Spiral Structure of the Outer Milky Way in Hydrogen

  title={The Spiral Structure of the Outer Milky Way in Hydrogen},
  author={Evan S. Levine and Leo Blitz and Carl Heiles},
  pages={1773 - 1777}
We produce a detailed map of the perturbed surface density of neutral hydrogen in the outer Milky Way disk, demonstrating that the Galaxy is a non-axisymmetric multiarmed spiral. Spiral structure in the southern half of the Galaxy can be traced out to at least 25 kiloparsecs, implying a minimum radius for the gas disk. Overdensities in the surface density are coincident with regions of reduced gas thickness. The ratio of the surface density to the local median surface density is relatively… Expand

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