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Monitoring Io volcanic Activity

Monitoring Io volcanic Activity. Franck Marchis Conor Laver, Imke de Pater (UC-Berkeley) Collaborators: A. Davies, E. Hom, R. Lopes. Outline. 2001-2002 monitoring (not again! - published Marchis et al. 2005) 2003-2004 Monitoring What happened in 2005? First OSIRIS data

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Monitoring Io volcanic Activity

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  1. Monitoring Io volcanic Activity Franck Marchis Conor Laver, Imke de Pater (UC-Berkeley) Collaborators: A. Davies, E. Hom, R. Lopes.

  2. Outline • 2001-2002 monitoring (not again! - published Marchis et al. 2005) • 2003-2004 Monitoring • What happened in 2005? • First OSIRIS data • Future AO for Keck and beyond

  3. Io in Near infrared • In JHK (1-2.5 mm)  surface features mainly seen (reflecting Sunlight) • In LM (3-5 mm) thermal output from eruptions • Brightness of hot spots in multiple bands  T and SA of active regions. z J H K L M

  4. 2003-2004 Monitoring The Keck Adaptive Optics instrument which provides high angular resolution images is a perfect tool to monitor the volcanic activity of Io. Data: Observations were recorded in imaging mode using the NIRC-2 infrared camera mounted on the Keck-10m AO system through several filters spanning 1-5 mm on January 26, 2003, March 8, 2003, and May 27-30, 2004. • At l < 2.5 mm in J (1. 2 mm), H (1.6 mm), K (2.2 mm) bands, albedo surface features (paterae, pyroclastic deposit fields) are visible with a spatial resolution ~150 km • At l > 3 mm, Lp (3.7 mm) & Ms (4.8 mm) bands, the thermal signatures of active volcanoes (T~500 K) dominate the image. Analysis: After enhancing the image sharpness with AIDA (Hom et al., 2005) or MISTRAL (Mugnier et al., 2004) algorithms, the position and brightness of individual hot spots were determined.

  5. Jan. 26 2003Observations 9 active centers were seen on one hemisphere (CML=73o). Several of them (A,B,D,E,F,G,H) were active during the Keck Dec. 2001 survey (Marchis et al., 2004) and the Galileo orbits (Lopes et al. 2004) Janus: I=11+/-1 GW/sr/umarginal in K band

  6. March 08 2003 SSI/Galileo reconstructed image Among 6 active centers detected on this hemisphere (CML= 145o), 5 (A,B,C,D,E,F) were seen active in the last 3 years.

  7. May 2004 • Four nights of Observations (May 27-30)

  8. May 2004 360 180 • 18 hot spots were detected on the ~70% of the entire satellite surface. 12 of them are considered as persistent (Lopes-Gautier, 1997 and Marchis et al. 2004). Their temperature and surface are estimated by a one-T black body fit (Taver~500 K). Loki (Q), the most active Ionian volcano, exhibits a low activity in contrast to previous long-term studies (Rathbun et. al.,2003, Howell et al., 2001).

  9. May 2004 Intensities are preliminary Contact me, please! * Or Angpetu

  10. Hot spot ‘0405A’ Detected May 28&May 30, 20046.3 W, 17.5SBrightness in Lp:59.3 +/- 2.1 GW/sr/micron&52.8 +/- 1.8 GW/sr/micronBrightness in Ms:63.5 +/- 16 GW/sr/micron&67.3 +/- 14.1 GW/sr/micronBrightness in Kc:1.8 +/- 0.1GW/sr/micronBrightness in H:0.8 +/- 0.1GW/sr/micron Rate of aerial coverage = 1561 m2/s Total area = 921 km2 Age of surface = 163 hours ~ 6 days T = 1475 to 300K Total Output: = 2.4 x 1012 W = 2.5% Io total thermal output

  11. What happened in 2005? • Most of our Keck nights were lost due to bad weather. One snapshot of Io in July 15 revealed a bright hot spot (close to Svarog) • Alarm program initiated in 2004. ToO time granted on VLT/NACO on two years. -> no detection unfortunately ~25 observations at Lick -> no outburst

  12. OSIRIS instrument • Integral Field spectrograph designed to work with Keck OA • Commissioned in 2005B, offered in 2006A • R~3400 with an angular resolution of 0.1” in z, J H K band

  13. OSIRIS

  14. Io seen through OSIRIS • Proposal submitted for 2006A (PI: I. de Pater) • C. Laver, graduate student Thesis project • April 2006 -> snapshot of Io • June 2006 -> 2 x half nights dedicated to Io (both hemispheres) • Results presented here are very preliminary!

  15. April 2006 Run • Mode used Kbb (1.965 m -2.381 m) • 0.05” scale -> FOV= 0.56” x 2.24” • Mosaic composed of 2 images • 20060417 at 09:13 UT • Center on Sigurd patera (CML=258o in planetocentric) • CML= 360-258 = 102o in planetographic referential

  16. A B April 2006 Run averaged image Summing up spectra Processed by C. Laver • 2 hot spots detected: • 20060417A - 2% Io total brightness (Dazhbog Regio) • 20060417B - faint - close to Hi’iaka

  17. April 2006 Run averaged image Summing up spectra Albedo feature -> Bosphorus Regio

  18. April 2006 Run SO2 lines at 1.982 m and 2.125 m(Schmitt et al., 1994) detected on the spectra Preliminary work by C. Laver C. Laver

  19. June 2006 Run • Observations in Hbb (1.473-1.803 m), Kbb (1.965-2.381) • FOV: 0.32” x 1.28” (0.01” / pixel) • Global mosaic made of 6 images ~40 min/spectra • 2 half-nights • 20060601 • 20060602 centered ~SEP longitude of ~100 degrees Animation by C. Laver 72 images through Kbb No tellurical correction yets ~40 min to scan

  20. June 2006 Run • 20060601 CML~108o • Pele (caldera, ring), Loki, Svarog • No bright hot spot Averaged H band Averaged K band Mosaic by C. Laver

  21. June 2006 run Observations in June 02 (CML~100o) • 20060417A is still active & detectable! • 20060417B is not…

  22. 20060417Aawakening of Tvashtar Most likely candidate: Tvashtar (60N+/-3, 120.3+/-5.5W) Spectra from 0.9-2.5 m recorded (analysis in progress…)

  23. Positions in agreement • 0914 UT 120.4+/-4 63.6+/- 5 • 0732 UT120.3+/- 5.4 60.0+/-3.3 Will be refined…

  24. Future work • OSIRIS data • Hot spot spectra • Compositional maps (SO2 and others?) • NIRC2 observations • Continue to monitor Io when at telescope • Publish our 2003-2005 monitoring result • Observations in coordination with New Horizon flyby submitted to ESO (VLT/NACO) • Imaging (PI. J. Spencer) • Spectroscopy (PI: K.L. Jessup) • New Generation of AO at Keck • Make sure that planetary science will be considered

  25. Next generation of AO systems • High quality AO system providing a perfect correction in JHK (SR>85%) and median in visible (SR>30%) Spatial resolution 90 km Spatial resolution 45 km

  26. Next generation of AO systems • High quality AO system providing a perfect correction in JHK and median in visible • First light before 2012!

  27. Next Generation of ground-based telescopes TMT - available in 2014 ? Spatial resolution 45 km in NIR 10 km in visible

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