Near-Infrared H2 and Continuum Survey of Extended Green Objects
  The Spitzer GLIMPSE survey has revealed a number of "Extended Green Objects"
(EGOs) which display extended emission at 4.5 micron. These EGOs are potential
candidates for high mass protostellar outflows. We have used high resolution (<
1") H2 1-0 S(1) line, K, and H-band images from the United Kingdom Infrared
Telescope to study 34 EGOs to investigate their nature. We found that 12 EGOs
exhibit H2 outflows (two with chains of H2 knotty structures; five with
extended H2 bipolar structures; three with extended H2 lobes; two with pairs of
H2 knots). In the 12 EGOs with H2 outflows, three of them exhibit similar
morphologies between the 4.5 micron and H2 emission. However, the remaining 9
EGOs show that the H2 features are more extended than the continuum features,
and the H2 emission is seldom associated with continuum emission. Furthermore,
the morphologies of the near-infrared continuum and 4.5 micron emission are
similar to each other for those EGOs with K-band emission, implying that at
least a part of the IRAC-band continuum emission of EGOs comes from scattered
light from the embedded YSOs.
