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Science 4 October 1985:
Vol. 230. no. 4721, pp. 65 - 69
DOI: 10.1126/science.230.4721.65
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Articles

Characterization of Io's Volcanic Activity by Infrared Polarimetry

JAY D. GOGUEN 1 and WILLIAM M. SINTON 1

1 University of Hawaii, Institute for Astronomy, Honolulu 96822

The thermal emission from Io's volcanic hot spots is linearly polarized. Infrared measurements at 4.76 micrometers show disk-integrated polarization as large as 1.6 percent. The degree and position angle of linear polarization vary with Io's rotation in a manner characteristic of emission from a small number of hot spots. A model incorporating three hot spots best fits the data. The largest of these hot spots lies to the northeast of Loki Patera, as mapped from Voyager, and the other spot on the trailing hemisphere is near Ra Patera. The hot spot on the leading hemisphere corresponds to no named feature on the Voyager maps. The value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur.

Submitted on March 12, 1985
Accepted on July 26, 1985


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Infrared Speckle Observations of Io: An Eruption in the Loki Region.
R. R. Howell, R. R. HOWELL, and M. T. MCGINN (1985)
Science 230, 63-65
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