HR: 1340h
AN: V33C-1483    [Abstracts]
TI: Volcanic Activity of Io Monitored with Keck-10m AO in 2003-2004
AU: * Marchis, F
EM: fmarchis@berkeley.edu
AF: Department of Astronomy, UC-Berkeley 601 Campbell Hall, Berkeley, CA 94720-3411 United States
AU: Davies, A G
EM: Ashley.Davies@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AU: Gibbard, S G
EM: sgibbard@igpp.ucllnl.org
AF: Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550-9234 United States
AU: Le Mignant, D
EM: davidl@keck.hawaii.edu
AF: W. M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743 United States
AU: Lopes, R M
EM: Rosaly.M.Lopes@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AU: Macintosh, B
EM: bmac@inuit.ucllnl.org
AF: Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550-9234 United States
AU: de Pater, I
EM: imke@berkeley.edu
AF: Department of Astronomy, UC-Berkeley 601 Campbell Hall, Berkeley, CA 94720-3411 United States
AB: With the demise of the Galileo mission, the monitoring of Io volcanic activity lies in the hands of ground-based observers. Our group regularly observed Io with the Keck-10m Adaptive Optics (AO) system and its NIRC-2 camera at 1-5 microns wavelength range. The angular resolution achieved is 0.05" in Kc band (2.2 microns), i.e. 120-140 km on Io at opposition. Approximately 5 to 8 active volcanic centers are usually detected on one 3 or 5 microns AO image with a T between 500 and 1000 K. On rare occasions, we detected the thermal output at shorter wavelength (1-2.5 micron) indicating a colour temperature $>$1300 K. For instance, our data revealed the presence on Jan. 26, 2003, of a bright eruption close to Janus Patera (5$\pm$3S, 39$\pm$3W) with intensity in Lp band (3.8 micron) of 11$\pm$1 GW/sr/micron and $\sim$2 GW/sr/micron in Kc band (2.2 micron). Another bright eruption close to Tupan Patera (16$\pm$4S, 137$\pm$4W) was seen on Mar. 8, 2003 (UT) with a I(Lp)=18 $\pm$1 GW/sr/micron and I(Kc)$\sim$3 GW/sr/micron. More recently, data taken on May 28 and 30, 2004, show the thermal emission of an eruptive center (called 0405A) located at 17$\pm$2 S, 6$\pm$1W (close to Ilmarinera Patera which has never been seen active) with a I(Kc)$\sim$7 GW/sr/micron and I(Lp)=166$\pm$6 GW/sr/micron. This energetic eruption was also detected in H band (1.6 micron) with I(H)$\sim$3 GW/sr/micron. Because we obtained the brightness of these eruptions in at least three different wavelengths, we can perform a more precise analysis of their activity using a basaltic cooling lava flow model (Davies, 1996). In the case of 0405A, we can conclude that we are observing an episode of fire-fountaining (a young, hot event) whose total output is estimated to $\sim$9E12 W (i.e. 10% of Io average total output), more energetic than Tvashtar 2001. The source of these active centers and their activity will be compared with previous Galileo NIMS/SSI observations. We will conclude describing how the future use of AO technique will help to monitor and understand this extraterrestrial and exotic volcanism.
UR: http://astron.berkeley.edu/~fmarchis/Science/Io/
DE: 8400 VOLCANOLOGY
DE: 8419 Eruption monitoring (7280)
DE: 8450 Planetary volcanism (5480)
DE: 8494 Instruments and techniques
DE: 5464 Remote sensing
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting