Io and Europa Atmosphere and Io Torus Detection Through Occultations and Conjunctions Scott Degenhardt International Occultation Timing Association [email protected].

Io and Europa Atmosphere and Io Torus Detection Through Occultations and Conjunctions

Scott DegenhardtInternational Occultation Timing Association

[email protected]

2010 Annual IOTA MeetingDecember 3-5, 2010

Boston, MA area

Having purchased this after attending the2009 Society for Astronomical Sciences Conference,

I hatched some hair brained ideas….

Scotty’s logic:

1 lightcurve data point = a picture into a distant place

1 picture = 1000 words

and

then

1000 data point lightcurve X 1000 words = 1,000,000 words!!!

If…..

1 miniDV tape ~ 1 hour of video data

So…

Therefore!!!

Double Jupiter Mutual Event of Aug 7, 2009Io’s shadow eclipses Europa

23 minutes later Io occults Europa

Io

Europa

• An anomalous trend was detected in the 20090807 IoII.• Theories were proposed for possible sources of this anomaly.• Possible sources fell into 4 main categories:

1. Camera response2. Recording method3. Reduction method4. Extinction via Io’s atmosphere

• Experiments were designed to validate or refute each.• Using a model derived from the 20090807 lightcurve predictions of

atmospheric extinction were created for the upcoming 20090901 IoII, which did repeat the anomaly as predicted based on that atmospheric model.

3.6” = 6 Io radii

dimming

brightening

Europa’smotion

Europa

Io

IAEP (Io Atmospheric Extinction Project) was launched, a global plea for observations was made.

Degenhardt, S. et. al (2010), Io and Europa Atmosphere Detection through Jovian Mutual Events, The Society for Astronomical Sciences: Proceedings for the 29th Annual Symposium on Telescope Science, p. 91-100  http://scottysmightymini.com/IAEP/SAS2010_Io_Europa_Degenhardt.doc

IAEP RESULTS WERE PUBLISHED AND PRESENTED:

YouTube video in four parts of the SAS 2010 Power Point Presentation:Part 1: http://www.youtube.com/watch?v=LJE_V9JystoPart 2: http://www.youtube.com/watch?v=0BFRpbTc748Part 3: http://www.youtube.com/watch?v=02s4KIZ55NEPart 4: http://www.youtube.com/watch?v=UECOxlFKLVI

Typical lightcurve for extended wing data:

Io and Europa have dimmed intensity trends surrounding the occultation. (We dubbed this “lowered shoulders”)

Ganymede wing data displayed a brightening intensity trend surrounding the occultation. (We dubbed “raised shoulders”)

IAEP results:

11 observers 4 countries 53 data sets

28 individual events

Simulation indicates “raised shoulders” to be the nominal response to two merging intensities of near equal brightness.

raised shoulder = nonlinear camera response creating the non-flat wings.

preliminary investigation: source = region between the two airy disks

As the photons in the outer rings of the airy disks begin to overlap, previously undetected photon rates become detectable due to the doubling of the photon rate.

Photon Doubling Effect (PDE)

baseline intensity

PDE region (intensity above baseline between merging spots)

False color intensity profile of Io (left peak) and Europa (right peak)

A “light bridge” is clearly seen forming between the two merging spots

Preliminary wing trend conclusionPDE causes a nonlinear intensity increase as two airy

disks of near equal intensity merge resulting in raised shoulders.

Raised shoulders should be the nominal response for two merging intensities of near equal brightness.

Therefore lowered shoulders indicate an anomalous loss of intensity in the measurement aperture.

Now we need to identify the source of the loss of light…

This data analysis technique of the raw video intensity effectively single handedly eliminates nonlinear camera response, recording method, and

reduction technique as the source of lowered shoulders.

Europa (behind Io) experiences dimming as it nears Io.

Two photometry methods used:

Individual photometry:

A measurement aperture is placed on each moon individually. Individual intensities are normalized to a common moon.

Combined photometry:

One large aperture surrounds both target moons. Total intensity of the large measurement aperture is normalized to a common moon.

Possible sources fell into 4 main categories:1. Camera response2. Recording method3. Reduction method4. Extinction via Io’s atmosphere

Dimming source conclusion:o The source of the dimming has been linked to the moon being occulted by

Io or Europa.o The start of dimming and end of brightening defines boundaries of

extinctive material.o Moons being occulted by Io suffer extinction of their light when they are

within 5 to 30 Io radii of Io.o Moons being occulted by Europa suffer extinction within 22 to 30 Europa

radii of Europa.o Moons being occulted by Ganymede do not suffer extinction at these

same distances.o An asymmetry was noticed in the slope trend of the ingress/egress of

extinction in both Io and Europa lightcurves.

If Io was west of Jupiter and occulted a moon with its western limb:Ingress/egress > 1

If Io was east of Jupiter and occulted a moon with its western limb:Ingress/egress < 1

Conclusions on asymmetry of Io atmospheric extinction:

Occultations on Io’s Jupiter facing limb have longer extinction slopes.

Longer extinction indicates more extinction material.

More extinction material on Io’s Jupiter facing limb possibly implies a stream of material from Io towards Jupiter. This comes as no surprise given that Jupiter is called the “vacuum cleaner” of our solar system.

Why?

Why have these extinction events been missed for 400 years…?

Likely due to insufficient wing data surrounding Jupiter Mutual Events.

Lightcurve (b.) is the same event as (a.), only (a.) has just 6 minutes of wing data surrounding the occultation (typical of what is found in the NSDC IMCCE database).

How small can your system be?!

•20100104 UT marked the end of the JME cycle

•This was not the end of Jovian Extinction Events

•Occultation misses, i.e. conjunctions still provide opportunities for extinction measurements

•Conjunctions remove the camera response issues associated with merging spots.

•20100104 UT marked the end of the JME cycle

•This was not the end of Jovian Extinction Events

•Occultation misses, i.e. conjunctions still provide opportunities for extinction measurements

•Conjunctions remove the camera response issues associated with merging spots.

Io’s eastern and western Torus tips appear more dense due to an optical geometry where the Torus material is collimated to our line of sight.

160 Io radiiIo

Torus material

Collimated Torus material at the tip of Torus

Earth’s view

Torus of Io(viewed from above)

Schematic of a Torus Jovian Extinction Event (TJEE)

Data provided by Wayne Green

Io Spectra taken by John Menke

HOW CAN I PARTICIPATE?I see the following potential research that can be done now:

1.Detection of extinction through video recordings in modest equipment. Begin making plans now to observe the next round of Jupiter Mutual Event occultations in 2014.2.PDE experiments to better our understanding of our observed nonlinear intensity gain with merging spots.3.Detection of Io or Europa atmosphere through transits by any astrophotographer that carefully does his work.4.Data mining of IMCCE NSDC lightcurves, Hubble, Voyager, Galileo, and Don Parker images (just kidding Don!), all sorts of things to look for now that we have pointed it out to everyone in the paper.5.Jovian Extinction Event observations. Io Torus detection and modeling, and Io and Europa atmosphere modeling through conjunctions. 6.Spectroscopy of Torus extinction events.7.Think outside the box (or rather your box should have elastic walls and not cement)!

http://scottysmightymini.com/JEE/JEE.htm

[email protected]

You do not have to wait 4 years (2014) for the next

Jupiter Mutual Event Cycle to measure extinction!

Jovian Extinction Event predictions for 2010 are available here:

Salvador AguirreSonora, Mexico

Dave ClarkTexas, USA

Scott DegenhardtTennessee, USA

Scott DegenhardtTennessee, USA

Tony GeorgeOregon, USA

Donald ParkerFlorida, USA

Terry ReddingFlorida, USA

Andy ScheckMaryland, USA

Brad TimersonNew York, USA

Not pictured but submitting data sets:

Wayne Green – Colorado, USA

Mike Hoskinson – Alberta, Canada

John Menke – Maryland, USA

Roger Venable – Georgia, USA

FINAL CONCLUSION• Dimming trends of Io and Europa occultations have been linked to

atmospheric extinction of the light of the moon being occulted.

• Asymmetries of the slope of extinction have been noted.

• No extinction trend has been detected for Ganymede.

• Extinction events caused by the Torus of Io and conjunctions with Io and Europa are detectable, further validating the extinction hypothesis.

• A 3D model of these atmospheres should be possible by inverting the lightcurves derived by our observational method.

• Extinction detection is possible in modest equipment. Further photometric and spectroscopic data collection is a must to gain better statistical data on the material causing the extinction phenomenon.

• Detection of extinctive material around our Jupiter may have implications for other Jupiter like exoplanet research.