Io torus(tor -ŭs, toh -rŭs) See Io; Jupiter.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Io torus[¦ī‚ō ′tȯr·əs]
A doughnut-shaped region of dense plasma that orbits Jupiter at the radial distance of the satellite Io and results from ionization by solar ultraviolet radiation of gases emitted from Io in volcanic eruptions.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.