A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way

@article{McClureGriffiths2004ADE,
  title={A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way},
  author={N. M. McClure–Griffiths and John M. Dickey and Bryan M. Gaensler and Andrew Green},
  journal={The Astrophysical Journal Letters},
  year={2004},
  volume={607},
  pages={L127 - L130}
}
Using data from the Southern Galactic Plane Survey, we present a possible distant spiral arm in the fourth quadrant of the Milky Way. The very distinct and cohesive feature can be traced for over 70° as the most extreme positive velocity feature in the longitude-velocity diagram. The feature is at a Galactic radius between 18 and 24 kpc and appears to be the last major structure before the end of the H I disk. We compare the feature with a Galactic spiral model and show that it is well… 

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