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Title: NEAR-INFRARED H{sub 2} AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS. II. COMPLETE CENSUS FOR THE NORTHERN GALACTIC PLANE

We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al., based on near-infrared narrow H{sub 2} (2.122 μm) and continuum observations from the United Kingdom Infrared Telescope. This data set is three times larger than the one in our previous study and is unbiased by preselection. As discussed in the previous paper, the morphologies of the 4.5 μm emission generally resemble those of the near-infrared continuum, but are different from those of the H{sub 2} emission. Of our sample, only 28% of EGOs with H{sub 2} emission show similar morphologies between 4.5 μm and H{sub 2} emission. These results suggest that the 4.5 μm emission mainly comes from scattered continuum from the embedded young stellar objects, and partially from H{sub 2} emission. About half of EGOs are associated with H{sub 2} outflows, if the H{sub 2} outflow incompleteness is considered. The H{sub 2} outflow detection rate for EGOs with K-band detections (61%) is significantly higher than for those without K-band detections (36%). This difference may be due to the fact that both H{sub 2} and K-band emissions are associated with outflows, i.e., H{sub 2} emission and K-band continuum are associated with shocks andmore » outflow cavities, respectively. We also compared the correlation between the H{sub 2} outflows and Class I 44 GHz methanol masers from the literature. The methanol masers can be located upstream or downstream of the H{sub 2} outflows and some bright H{sub 2} spots or outflows are not associated with methanol masers, suggesting that methanol masers and H{sub 2} emission trace different excitation conditions.« less
Authors:
; ; ; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China)
  2. Department of Mechanical Engineering, National Taiwan University, 1 Roosevelt Rd., Section 4, Taipei 10617, Taiwan (China)
  3. Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH (United Kingdom)
  4. Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)
  5. Institute of Astronomy and Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan (China)
Publication Date:
OSTI Identifier:
22273309
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 208; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; CORRELATIONS; DETECTION; EXCITATION; GHZ RANGE; JETS; MASERS; METHANOL; MILKY WAY; MORPHOLOGY; NEAR INFRARED RADIATION; PHOTON EMISSION; STARS; TELESCOPES