Title

The Nucleus Of Comet Borrelly: A Study Of Morphology And Surface Brightness

Keywords

Comets; Morphology; Nucleus; Photometry; Surfaces; Topography

Abstract

Stereo images obtained during the DS1 flyby were analyzed to derive a topographic model for the nucleus of Comet 19P/Borrelly for morphologic and photometric studies. The elongated nucleus has an overall concave shape, resembling a peanut, with the lower end tilted towards the camera. The bimodal character of surface-slopes and curvatures support the idea that the nucleus is a gravitational aggregate, consisting of two fragments in contact. Our photometric modeling suggests that topographic shading effects on Borrelly's surface are very minor (<10%) at the given resolution of the terrain model. Instead, albedo effects are thought to dominate Borrelly's large variations in surface brightness. With 90% of the visible surface having single scattering albedos between 0.008 and 0.024, Borrelly is confirmed to be among the darkest of the known Solar System objects. Photometrically corrected images emphasize that the nucleus has distinct, contiguous terrains covered with either bright or dark, smooth or mottled materials. Also, mapping of the changes in surface brightness with phase angle suggests that terrain roughness at subpixel scale is not uniform over the nucleus. High surface roughness is noted in particular near the transition between the upper and lower end of the nucleus, as well as near the presumed source region of Borrelly's main jets. Borrelly's surface is complex and characterized by distinct types of materials that have different compositional and/or physical properties. © 2003 Elsevier Inc. All rights reserved.

Publication Date

1-1-2004

Publication Title

Icarus

Volume

167

Issue

1

Number of Pages

70-79

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.icarus.2003.05.001

Socpus ID

1642543335 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/1642543335

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