Electronic Telegram No. 3632
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


JUPITER I (IO)
     Imke de Pater and Mate Adamkovics, University of California at Berkeley;
and Ashley Gerard Davies, Jet Propulsion Laboratory, California Institute of
Technology, report the discovery of a large volcanic eruption on Jupiter I
(Io), at Rarog Patera, at a location near longitude 306 deg W, latitude -41
deg.  The observations were obtained with the near-infrared camera NIRC2,
coupled to the adaptive-optics system on the 10-m W. M. Keck II telescope on
Mauna Kea on 2013 Aug. 15.646 UT.  Flux densities measured at 1.6, 2.3, 3.8,
and 4.05 microns are about 290, 560, 180, and 250 GW/sr/micron, respectively.
A blackbody fit to the data indicates an effective temperature of about 1300 K,
over an area of about 30 square km.  The total power output is about 5 TW.
Fits of the Davies (1996, Icarus 124, 45) "Io Flow Model" indicate that the
eruption is very vigorous and the exposed surfaces are very young:  the oldest
surface exposed is only about 8 seconds.  The model fits suggest that lava
fountaining is taking place, a highly-energetic style of volcanism previously
observed on Io where incandescent lava fountains erupt along the length of a
fissure.  This eruption type is not only rare on Io but is particularly timely,
as it has occurred only two weeks prior to the launch of the EXCEED (Extreme
Ultraviolet Spectroscope for Exospheric Dynamics) telescope onboard the
Japanese Space Agency (JAXA) satellite SPRINT-A.  This spacecraft will observe
the Io plasma torus in the EUV for about six months, providing an excellent
opportunity to investigate how variations in the Io plasma torus may be
triggered by Io's volcanic activity.  Continued observations of this volcanic
eruption are encouraged to investigate its temporal evolution.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 August 17                   (CBET 3632)              Daniel W. E. Green