A Classification Scheme for Young Stellar Objects Using the WIDE-FIELD
  INFRARED SURVEY EXPLORER AllWISE Catalog: Revealing Low-Density Star
  Formation in the Outer Galaxy
  We present an assessment of the performance of WISE and the AllWISE data
release in a section of the Galactic Plane. We lay out an approach to
increasing the reliability of point source photometry extracted from the
AllWISE catalog in Galactic Plane regions using parameters provided in the
catalog. We use the resulting catalog to construct a new, revised young star
detection and classification scheme combining WISE and 2MASS near and
mid-infrared colors and magnitudes and test it in a section of the Outer Milky
Way. The clustering properties of the candidate Class I and II stars using a
nearest neighbor density calculation and the two-point correlation function
suggest that the majority of stars do form in massive star forming regions, and
any isolated mode of star formation is at most a small fraction of the total
star forming output of the Galaxy. We also show that the isolated component may
be very small and could represent the tail end of a single mechanism of star
formation in line with models of molecular cloud collapse with supersonic
turbulence and not a separate mode all to itself.
