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[volcanopele]

Titan's Enigmatic Infrared-Bright Spot Is Surface Make-Up
By Lori Stiles
October 06, 2005

http://uanews.org/cgi-bin/WebObjects/UANew...ArticleID=11813

A 300-mile-wide patch that outshines everything else on Titan at long infrared wavelengths appears not to be a mountain, a cloud or a geologically active hot spot, University of Arizona scientists and Cassini team members say.

"We must be looking at a difference in surface composition," said Jason W. Barnes, a postdoctoral researcher at UA's Lunar and Planetary Lab. "That's exciting because this is the first evidence that says not all of the bright areas on Titan are the same. Now we have to figure out what those differences are, what might have caused them."

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The paper, "A 5-Micron-Bright Spot on Titan: Evidence for Surface Diversity" is now published in Science:

http://www.sciencemag.org/cgi/content/abstract/310/5745/92

This article is about Hotei Arcus, an arc-shaped feature in southeastern Xanadu. This feature appears brighter than its surroundings in almost all wavelengths that see the surface, including ISS' 938-nm, but the feature appears exceptionally bright at 5-microns. Another feature with similar characteristics is Tui Regio. I've attached a few views from VIMS from Ta. A close-up of Tui Regio from ISS can be found here

[volcanopele]

Here is the attachment I promised. This graphic uses v1477475933 from the latest PDS release. This is a VIMS cube centered on Tui Regio in Southwestern Xanadu (no PDS release yet for Hotei Arcus). The first 7 images are slices of VIMS cubes are the labeled wavelength, from 0.933 microns out to 4.989 microns. Each of these is of course in a methane window. The next 5 are color composites with various wavelength combinations. Like Hotei, Tui is brighter than its surroundings at all wavelengths, but this albedo contrast is really significant at longer wavelengths as the rest of the surface darkens.

One thing I've noted looking at this cube is the various dark markings in the mid-latitudes of Titan and toward the south near the cloud field. However, the biggest surprise came with Kalseru Virga. This ~N-S stripe of bright material southwest of Tui Regio can be seen in ISS images, as well as in this VIMS cube, but it can only be seen at shorter wavelengths. At wavelengths longwards of 1.590 microns, this feature is not evident, however three dark markings, one near the northern part of Kalseru and two bounding the southern end, become more prominent. Very interesting!

Attached thumbnail(s)