NEAR-INFRARED H ₂ AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS

Abstract

The Spitzer GLIMPSE survey has revealed a number of "Extended Green Objects"\n(EGOs) which display extended emission at 4.5 micron. These EGOs are potential\ncandidates for high mass protostellar outflows. We have used high resolution (<\n1") H2 1-0 S(1) line, K, and H-band images from the United Kingdom Infrared\nTelescope to study 34 EGOs to investigate their nature. We found that 12 EGOs\nexhibit H2 outflows (two with chains of H2 knotty structures; five with\nextended H2 bipolar structures; three with extended H2 lobes; two with pairs of\nH2 knots). In the 12 EGOs with H2 outflows, three of them exhibit similar\nmorphologies between the 4.5 micron and H2 emission. However, the remaining 9\nEGOs show that the H2 features are more extended than the continuum features,\nand the H2 emission is seldom associated with continuum emission. Furthermore,\nthe morphologies of the near-infrared continuum and 4.5 micron emission are\nsimilar to each other for those EGOs with K-band emission, implying that at\nleast a part of the IRAC-band continuum emission of EGOs comes from scattered\nlight from the embedded YSOs.\n