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Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grainsThe Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Witt, Adolf N. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Petersohn, Jens K. (Toledo Univ. OH, United States)
Bohlin, Ralph C. (Space Telescope Science Inst. Baltimore, MD, United States)
O'Connell, Robert W. (Virginia Univ. Charlottesville, United States)
Roberts, Morton S. (National Radio Astronomy Observatory Charlottesville, VA, United States)
Smith, Andrew M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Stecher, Theodore P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 15, 2013
Publication Date
August 10, 1992
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 395
Issue: 1
ISSN: 0004-637X
Subject Category
Distribution Limits