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Near-infrared H2 and continuum survey of extended green objects. II. Complete census for the northern Galactic plane

Lee, Hsu-Tai, Liao, Wei-Ting, Froebrich, Dirk, Karr, Jennifer, Ioannidis, Georgios, Lee, Yong-Hyun, Su, Yu-Nung, Liu, Sheng-Yuan, Duan, Hao-Yuan, Takami, Michihiro and others. (2013) Near-infrared H2 and continuum survey of extended green objects. II. Complete census for the northern Galactic plane. Astrophysical Journal Supplement Series, 208 (2). pp. 1-53. ISSN 0067-0049. E-ISSN 1538-4365. (doi:10.1088/0067-0049/208/2/23)

Abstract

We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al., based on near-infrared narrow H2 (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 H2 emission. Of our sample, only 28% of EGOs with H2 emission show similar morphologies between 4.5 μm and H2 emission. These results suggest that the 4.5 μm emission mainly comes from scattered continuum from the embedded young stellar objects, and partially from H2 emission. About half of EGOs are associated with H2 outflows, if the H 2 outflow incompleteness is considered. The H2 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 H2 and K-band emissions are associated with outflows, i.e., H2 emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H2 outflows and Class I 44 GHz methanol masers from the literature. The methanol masers can be located upstream or downstream of the H2 outflows and some bright H2 spots or outflows are not associated with methanol masers, suggesting that methanol masers and H 2 emission trace different excitation conditions. © 2013. The American Astronomical Society. All rights reserved..

Item Type: Article
DOI/Identification number: 10.1088/0067-0049/208/2/23
Additional information: Unmapped bibliographic data: C7 - 23 [EPrints field already has value set] LA - English [Field not mapped to EPrints] J2 - Astrophys. J. Suppl. Ser. [Field not mapped to EPrints] AD - Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan [Field not mapped to EPrints] AD - Department of Mechanical Engineering, National Taiwan University, 1 Roosevelt Rd., Taipei 10617, Taiwan [Field not mapped to EPrints] AD - Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH, United Kingdom [Field not mapped to EPrints] AD - Department of Physics and Astronomy, Seoul National University, Seoul 151-742, South Korea [Field not mapped to EPrints] AD - Institute of Astronomy, Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan [Field not mapped to EPrints] AD - University of Illinois at Urbana-Champaign, United States [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: infrared: stars, ISM: jets and outflows, stars: formation
Subjects: Q Science > QB Astronomy
Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Giles Tarver
Date Deposited: 20 Jul 2015 15:52 UTC
Last Modified: 29 May 2019 14:51 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/49555 (The current URI for this page, for reference purposes)
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