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7.6. Dust composition, energetics, and morphology of the Galactic center

Published online by Cambridge University Press:  25 May 2016

Kin-Wing Chan
Affiliation:
NASA/Ames Research Center MS 245-6, Moffett Field, CA 94035, USA
S. H. Moseley
Affiliation:
NASA/Goddard Space Flight Center Code 685, Greenbelt, MD 20771, USA
S. Casey
Affiliation:
Hughes/STX/NASA/Goddard Space Flight Center Code 685, Greenbelt, MD 20771, USA
J. P. Harrington
Affiliation:
University of Maryland Dept. of Astronomy, College Park, MD 20742, USA
E. Dwek
Affiliation:
NASA/Goddard Space Flight Center Code 685, Greenbelt, MD 20771, USA
R. Loewenstein
Affiliation:
Yerkes Observatory William Bay, Wisconsin, WI 53191, USA
F. Városi
Affiliation:
Hughes/STX/NASA/Goddard Space Flight Center Code 685, Greenbelt, MD 20771, USA
W. Glaccum
Affiliation:
Applied Research Corporation 8201 Corporate Drive, Landover, MD 20785, USA

Abstract

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Spectra at 16 - 45 μm of several regions within the central 80″ of the Galaxy have been obtained at 20″ resolution using the Goddard Cryogenic Grating Spectrometer No. 2 on the Kuiper Airborne Observatory. A broad band of excess emission extending from 24 to 45 μm is present in the spectra at positions covering the “tongue” and the inner edge of the circumnuclear disk. A similar dust emission feature has been observed in some carbon-rich evolved stars and in a nitrogen-rich evolved massive star. The observations reported here are the first detection of this dust emission feature in the interstellar medium. After considering several possible candidates of the carrier for this 30 μm dust feature, we find that MgS is the best owing to its good fit to the observed spectra. The origin of this ~ 30 μm feature in the Galactic center is unknown. Based on the theoretical results of dust condensation and elemental abundances in a supernova, we find that the supernovae in the central 500 pc could provide the amount of MgS dust, which we proposed as the carrier of the 30 μm dust feature, observed in the central 3 pc.

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