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7.13. The Sgr A East HII complex and associated features

Published online by Cambridge University Press:  25 May 2016

Keven I. Uchida
Affiliation:
The Ohio State University
Mark R. Morris
Affiliation:
University of California at Los Angeles
Gene Serabyn
Affiliation:
California Institute of Technology
David Fong
Affiliation:
University of Illinois at Urbana Champaigne
Thomas Meseroll
Affiliation:
Hughes Aircraft Corporation

Extract

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The Sgr A East H ii complex consists of 4 compact H ii regions situated just east of and following, in an arc pattern, the edge of the Sgr A East nonthermal shell. Located between the arc of H ii regions and the nonthermal shell is a dense molecular ridge – presumably compressed – known as the “50 km/s cloud”. The hypothesis that these H ii regions delineate massive star formation provoked by the rapid expansion of Sgr A East into the molecular cloud is problematical because of the mismatch of the shell expansion and star formation time scales. We therefore examine the alternative hypothesis that Sgr A East is a quasi-static or slowly expanding structure fed from within by the release of relativistic particles from sources at or near the nucleus. The elongation of SgrA East along the Galactic plane is ascribed to the shear inherent in the velocity field this close to the Galactic center (GC). In this proceeding we discuss our ongoing efforts to model the effects of shear in detail, using the elongation of Sgr A East to constrain its expansion time scale.

Type
Part II. Nuclear Interstellar Medium
Copyright
Copyright © Kluwer 1998 

References

Tenorio-Tagle, G. & Palous, J. 1987, A&A 186, 287.Google Scholar
Uchida, K.I., Morris, M., Bally, J., Pound, M., & Yusef-Zadeh, F. 1992, ApJ, 398, 128.CrossRefGoogle Scholar