Monitoring Io volcanic Activity

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Monitoring Io volcanic Activity

• Franck Marchis
• Conor Laver, Imke de Pater (UC-Berkeley)
• Collaborators A. Davies, E. Hom, R. Lopes.

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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

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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.

J H K L M
z
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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 lt 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 gt 3 mm, Lp (3.7 mm) Ms (4.8 mm) bands, the
  thermal signatures of active volcanoes (T500 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.

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Jan. 26 2003Observations

• 9 active centers were seen on one hemisphere
  (CML73o). 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 I11/-1 GW/sr/?umarginal in K band
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March 08 2003

• 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.

SSI/Galileo reconstructed image
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May 2004

• Four nights of Observations (May 27-30)

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May 2004

• 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
  (Taver500 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).

360
180
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May 2004
Intensities are preliminary Contact me, please!
Label Date of Obs. Coordinates Intensity In L (GW/sr/mm) Intensity In M (GW/sr/mm) Candidate1 Best T (K) Surface Area (km2)
D May 27 83.9W,2.3N 1.60.3 2.90.9 Hiiaka 445 55 1
E May 27 95.4W,16.0N 0.70.3 1.90.4 Gish Bar 300 1300 250
F May 27 118.5W,22.3N 2.20.5 4.20.7 Amirani 485 41 3
G May 27 132.3W,33.8S 0.60.1 1.20.2 Malik 435 25 1
H May 27 144.3W,17.4S 1.20.4 1.50.1 Tupan 590 5 1
I May 27 158.0W,0.6S 1.90.3 4.10.9 Prometheus 410 139 1
A May 28 6.3W,17.5S 59 2 6416 Ilmarinera gt860 37X 4X
P May 28 309.7,37.1N 3.40.7 14.71.1 Amaterasu 310 5287500
Q May 28 311.6W,14.0N 11.40.8 404 Loki 315 1328316
R May 28 344.3W,51.7S 9.40.7 251 Creidne 380 1501 100
Or Angpetu
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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 /- 0.1
  GW/sr/micron Brightness in H 0.8 /- 0.1
  GW/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
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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.
• -gt no detection unfortunately

25 observations at Lick -gt no outburst
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OSIRIS instrument

• Integral Field spectrograph designed to work with
  Keck OA
• Commissioned in 2005B, offered in 2006A
• R3400 with an angular resolution of 0.1 in z, J
  H K band

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OSIRIS
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Io seen through OSIRIS

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

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April 2006 Run

• Mode used Kbb (1.965 ?m -2.381 ?m)
• 0.05 scale -gt FOV 0.56 x 2.24
• Mosaic composed of 2 images
• 20060417 at 0913 UT
• Center on Sigurd patera (CML258o in
  planetocentric)
• CML 360-258 102o in planetographic referential

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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 Hiiaka

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April 2006 Run
averaged image Summing up spectra
Albedo feature -gt Bosphorus Regio
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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
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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
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June 2006 Run

• 20060601 CML108o
• Pele (caldera, ring), Loki, Svarog
• No bright hot spot

Averaged H band
Averaged K band
Mosaic by C. Laver
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June 2006 run

• Observations in June 02 (CML100o)
• 20060417A is still active detectable!
• 20060417B is not

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20060417Aawakening of Tvashtar
Most likely candidate Tvashtar (60N/-3,
120.3/-5.5W) Spectra from 0.9-2.5 ?m recorded
(analysis in progress)
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Positions in agreement

• 0914 UT
• 120.4/-4 63.6/- 5
• 0732 UT120.3/- 5.4 60.0/-3.3

Will be refined
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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

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Next generation of AO systems

• High quality AO system providing a perfect
  correction in JHK (SRgt85) and median in visible
  (SRgt30)

Spatial resolution 90 km
Spatial resolution 45 km
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Next generation of AO systems

• High quality AO system providing a perfect
  correction in JHK and median in visible

• First light before 2012!

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