Jovian Extinction Events JPL Confirmation of JEE Data. Jovian Extinction Events JPL Confirmation of JEE Data. Modeling the Jovian dust field, moon atmospheres, flux tubes and Io’s Torus 2013 Annual IOTA Meeting, October 4-6, 2013 Toronto, Ontario, Canada

What is a JEE? Jovian Extinction Event describes a dimming in photometry lightcurves as objects pass behind regions of gas and dust associated with the Jovian System. Since the discovery of this phenomenon about 100 data sets have been acquired from 6 different countries documenting atmospheric diameters and densities surrounding moons and gas and dust trapped in the Torus of Io.

Can video provide accurate photometry? When used within its limits, photometry with video is possible as we will demonstrate. Collaborating with Arne Henden (AAVSO Director) his initial estimates were that video photometry would likely be able to reach magnitude standard deviations. Using techniques derived from Brian Warner’s “Lightcurve Photometry and Analysis” and years of video experiences we routinely achieve magnitude standard deviation.

How we record and process video NTSC video produce frames per second, 25 frames per second at 8 bit resolution. Using carefully placed background and measurements apertures in video photometry reduction software such as LiMovie we obtain a background corrected photometry measurement for each individual frame. To significantly reduce scintillation and other noise contributions we then bin 10 seconds of data into a single data point, i.e. 300 frames for NTSC or 250 frames for PAL into one point. This yields 256 x 300 = 76,800 or > 16 bit statistical resolution, easily reaching magnitude stnd dev.

165 minutes Jupiter’s elevation 18°52°

Proposed source of dimming: Reduction techniques introduce a dimming trend as two intensity sources merge.

Proposed source of dimming: Reduction techniques introduce a dimming trend as two intensity sources merge.

We can eliminate reduction technique as the source of dimming Raw 3D intensity profile shows Europa dim as it passed behind Io.

Separate photometry confirms Europa dimming

2 different reduction methods from 2 different observations of the same event yield identical overlapping trends.

Proposed source of dimming: Camera response introduce a dimming trend as two intensity sources merge. This implies one of two things: 1) Either the anomaly is introduced randomly as a result of two merging light sources. or 2) It is systematically introduced and would be tied to the field of view geometry, i.e. a specific pixel spacing produces a specific intensity anomaly.

Proposed source of dimming: Camera response introduce a dimming trend as two intensity sources merge. This implies one of two things: 1) Either the anomaly is introduced randomly as a result of two merging light sources. or 2) It is systematically introduced and would be tied to the field of view geometry, i.e. a specific pixel spacing produces a specific intensity anomaly.

2 vastly different field of views of the same event yield the same JEE trend.

Consistent results, not random:

Removing merging sources we still find extinction. Io suffers self extinction in its Torus.

JEE2010 After finding repeated atmospheric extinction JEEs, PI Degenhardt theorized that the Torus material of Io should cause Io to self extinct at the tips of the Torus where the material is line of sight collimated.

Observations were made and ~ 0.13 magnitude drop has been documented during tip crossings and we have derived a model for this extinction rate.

All these are just squiggly lines unless they can be linked to the Jovian system… Ahhhhhh, thanks to JPL we can do that! The ephemeris they use to guide our spacecraft is available free to anyone.

JEE2012 Major shift using JPL ephemeris Recent introduction by Wayne Green of the Horizons JPL ephemeris for the accurate data of Jovian moons has revolutionized our data reduction and future prediction methods. Reducing all past JEE lightcurves by overlaying the intensity data on top of JPL ephemeris has derived potentially useful scientific data.

Sample JEE lightcurve Using JPL data we can create an O-C comparison Sample JEE lightcurve Using JPL data we can create an O-C comparison

This is a sample “envelope” of extinction based on published atmospheric model size for Io. There are no published values for extinction, so we used a range of 0.1 to 0.5 magnitude loss due to extinction overlaid on the JPL ephemeris. This is a sample “envelope” of extinction based on published atmospheric model size for Io. There are no published values for extinction, so we used a range of 0.1 to 0.5 magnitude loss due to extinction overlaid on the JPL ephemeris.

The JEE data is in the envelope, a fit is then performed using JPL ephemeris

Using JPL ephemeris

Taking this data we can model the Torus of Io in the next image

The Hubble Challenge Why can’t I see the atmosphere surrounding Io when it transits Jupiter? Question: Answer: Absolutely you can… you just have to looking the right way!

1 Io radii 7.5 Io radii A sample check of the gradient of intensity surrounding Io shows the same linear extinction out to 7.5 Io radii, the same average value we derived in Raw Hubble image of an Io transit

Magnitude rise = 0.12 A linear fit of the intensity change derives an estimated rise of 0.12 magnitude, in the ballpark of our JEE measurements. Such a small magnitude gradient against an object usually about -2 magnitude is hardly obvious, but not undetectable with the right methods. A linear fit of the intensity change derives an estimated rise of 0.12 magnitude, in the ballpark of our JEE measurements. Such a small magnitude gradient against an object usually about -2 magnitude is hardly obvious, but not undetectable with the right methods. Raw Hubble image of an Io transit

Conclusions Video data used within its limits is capable of magnitude standard deviation. Anomalous dimming are independent of camera, observing system or reduction technique. O-C comparisons to JPL Horizons ephemeris show the JEE phenomenon is linked to consistent geometries of the Jovian System. Raw images from the Hubble Space Telescope of Io transits reveal intensity gradients surrounding Io consistent with JEE data.

Conclusions (Cont.) JEE atmosphere diameter measurements: Io: ~8 Io radii Europa: ~18 Europa radii Ganymede: none detected so far Consistent with published diameters.

Observe! Predictions, results, and discussions Yahoo Discussion Group JEE_Talk

Appendix I have added reduced lightcurves here just for extra data review.

AAVSO Alert Notice 464: Observers requested for Jovian Extinction Events (JEE2012), Arlot, J.-E., Thuillot, W.,Ruatti, C. and 116 coauthors observers of events: 2009, The PHEMU03 catalogue of observations of the mutual phenomena of the Galilean satellites of Jupiter, Astronomy and Astrophysics, Volume 493, Issue 3, pp Michael E. Brown & Richard E. Hill Discovery of an extended sodium atmosphere around Europa Nature 380, (21 March 1996); doi: /380229a0 Burger, M.H. et al. “Mutual Event Observations of Io's Sodium Corona” (2001) 37X/563/2/1063/52792.text.html Burger, M.H. et al. “Europa’s neutral cloud: morphology and comparisons to Io Matthew H. Burger & Robert E. Johnson” Icarus 171 (2004) 557–560, Degenhardt, S. et. al (2010), Io and Europa Atmosphere Detection through Jovian Mutual Events, The Society for Astronomical Science: Proceedings for the 29th Annual Symposium on Telescope Science, p Degenhardt, S.M., “JEE2012 Call for Observers” (2012) Degenhardt, S.M., “JEE2013 Call for Observers” (2012) Degenhardt, S.M. (2012), Yahoo Discussion Group JEE_Talk, Degenhardt, S. M., Jovian Extinction Event Predictions and Reduction Methods, Author and developer: Observations and data from S. Aguirre, S. Degenhardt, M. Hoskinson, A. Scheck, B. Timerson, D. Clark, T. Redding, J. Talbot, JPL Horizons On-Line Degenhardt, S.M., “Io atmospheric extinction predictions for 2009 Jovian Mutual Events” (2009) References

Degenhardt, S.M., “Jovian Extinction Event (JEE) predictions for 2010” (2010) Kuznetsov, A.A. et. al, “Formation of zebra pattern in low-frequency Jovian radio emission” (2012), arXiv: v1 [astro- ph.EP], Planetary & Space Science Lang, K.R., flux tube diagram, (2010) Lersch, Thomas, Zebra photo, LiMovie Miyashita, K., LiMovie, (2008) software to photometrically reduce AVIs. net.ne.jp/k_miyash/occ02/limovie_en.html NASA, Juno Space Probe Mission, NSDC (Natural Satellites Data Center) database web address: Schneider, N. M. et al., “The structure of Io's corona” (1991), ApJ, 368, 298 Solar System Dynamics Group, Horizons On-Line Ephemeris System, Author : Warner, B., “Lightcurve Photometry and Analysis”, (2006), Springer Science+Media, Inc. References (cont.)