New discoveries by the James Webb Area Telescope have unveiled secrets and techniques about Jupiter’s largest moon, Ganymede, and probably the most volcanically energetic one, Io. The findings embrace proof of the peroxide being produced by charged particles impacting the ice on Ganymede, and new observations of ongoing eruptions on Io. Credit score: Ganymede: Samantha Trumbo, Cornell; Io: Imke de Pater, UC Berkeley
Groundbreaking observations by the James Webb Area Telescope have revealed hydrogen peroxide on Ganymede and ongoing volcanic eruptions on Io, enhancing our understanding of Jupiter’s moons and the broader photo voltaic system.
With its delicate infrared cameras and high-resolution spectrometer, the James Webb Area Telescope (JWST) is revealing new secrets and techniques of Jupiter’s Galilean satellites, specifically Ganymede, the biggest moon, and Io, probably the most volcanically energetic.
In two separate publications, astronomers who’re a part of JWST’s Early Launch Science program report the primary detection of hydrogen peroxide on Ganymede and sulfurous fumes on Io, each the results of Jupiter’s domineering affect.
“This reveals that we are able to do unimaginable science with the James Webb Area Telescope on photo voltaic system objects, even when the thing is basically very vivid, like Jupiter, but additionally whenever you have a look at very faint issues subsequent to Jupiter,” mentioned Imke de Pater, professor emerita of astronomy and earth and planetary science on the College of California, Berkeley. De Pater and Thierry Fouchet from the Paris Observatory are co-principal investigators for the Early Launch Science photo voltaic system statement workforce, one in all 13 groups given early entry to the telescope.
A spectroscopic map of Ganymede derived from JWST measurements reveals mild absorption across the poles attribute of the molecule hydrogen peroxide. The circle outlines the surfaces of the moon. Credit score: Samantha Trumbo, Cornell
Ganymede’s Hydrogen Peroxide Research
Samantha Trumbo, a 51 Pegasi b postdoctoral fellow at Cornell College, led the examine of Ganymede, which was printed on July 21 within the journal Science Advances. Utilizing measurements captured by the close to infrared spectrometer (NIRSpec) on JWST, the workforce detected the absorption of sunshine by hydrogen peroxide — H2O2 — across the north and south poles of the moon, a results of charged particles round Jupiter and Ganymede impacting the ice that blankets the moon.
“JWST revealing the presence of hydrogen peroxide at Ganymede’s poles reveals for the primary time that charged particles funneled alongside Ganymede’s magnetic subject are preferentially altering the floor chemistry of its polar caps,” Trumbo mentioned.
The astronomers argue that the peroxide is produced by charged particles hitting the frozen water ice across the poles and breaking the water molecules into fragments — a course of known as radiolysis — which then recombine to kind H2O2. They suspected that radiolysis would happen primarily across the poles on Ganymede as a result of, not like all different moons in our photo voltaic system, it has a magnetic subject that directs charged particles towards the poles.
Closeup photographs of Ganymede (left), taken by NASA’s Juno spacecraft in 2021, and Io (proper), taken by NASA’s Galileo spacecraft in 1997. Credit score: NASA/JPL/USGS
Magnetic Subject and Comparability with Europa
“Similar to how Earth’s magnetic subject directs charged particles from the solar to the very best latitudes, inflicting the aurora, Ganymede’s magnetic subject does the identical factor to charged particles from Jupiter’s magnetosphere,” she added. “Not solely do these particles end in aurorae at Ganymede, as effectively, however in addition they impression the icy floor.”
Trumbo and Michael Brown, professor of planetary astronomy at Caltech, the place Trumbo just lately obtained her Ph.D., had earlier studied hydrogen peroxide on Europa, one other of Jupiter’s 4 Galilean satellites. On Europa, nevertheless, the peroxide was detectable over a lot of the floor, maybe, partly, as a result of it has no magnetic subject to guard the floor from the fast-moving particles zipping round Jupiter.
Implications for Outer Photo voltaic System
“That is seemingly a very vital and widespread course of,” Trumbo mentioned. “These observations of Ganymede present a key window to grasp how such water radiolysis would possibly drive chemistry on icy our bodies all through the outer photo voltaic system, together with on neighboring Europa and Callisto (the fourth Galilean moon).”
“It helps to truly perceive how this so-called radiolysis works and that, certainly, it really works as folks anticipated, primarily based on lab experiments on Earth,” de Pater mentioned.
A JWST infrared picture of Io reveals scorching volcanic eruptions at Kanehekili Fluctus (heart) and Loki Patera (proper). The circle outlines the floor of the moon. Credit score: Imke de Pater, UC Berkeley
Io’s Sulfurous Setting
In a second paper, accepted for publication within the journal JGR: Planets, a publication of the American Geophysical Union, de Pater and her colleagues report new Webb observations of Io that present a number of ongoing eruptions, together with a brightening at a volcanic advanced known as Loki Patera and an exceptionally vivid eruption at Kanehekili Fluctus. As a result of Io is the one volcanically energetic moon within the photo voltaic system — Jupiter’s gravitational push and pull heats it up — research like this give planetary scientists a special perspective than may be obtained by finding out volcanos on Earth.
For the primary time, the researchers had been capable of hyperlink a volcanic eruption — at Kanehekili Fluctus — to a selected emission line, a so-called “forbidden” line, of the gasoline sulfur monoxide (SO).
JWST measurements obtained in November 2022 overlaid on a map of Io’s floor. Thermal infrared measurements (left) present a brightening of Kanekehili Fluctus, a big and, through the statement interval, very energetic volcanic space on Io. Spectral measurements (proper) present forbidden infrared emissions from sulfur monoxide centered on the volcanic space. The coincidence confirms a concept that SO is produced in volcanic vents and, within the very skinny ambiance of Io, stay round lengthy sufficient to emit the forbidden line that will usually be suppressed by collisions with different molecules within the ambiance. Credit score: Chris Moeckel and Imke de Pater, UC Berkeley; Io map courtesy of USGS
Understanding Io’s Ambiance
Sulfur dioxide (SO2) is the primary element of Io’s ambiance, coming from sublimation of SO2 ice, in addition to ongoing volcanic eruptions, much like the manufacturing of SO2 by volcanos on Earth. The volcanos additionally produce SO, which is far more durable to detect than SO2. Specifically, the forbidden SO emission line may be very weak as a result of SO is in such low concentrations and produced for less than a short while after being excited. Furthermore, the observations can solely be made when Io is in Jupiter’s shadow, when it’s simpler to see the glowing SO gases. When Io is in Jupiter’s shadow, the SO2 gasoline in Io’s ambiance freezes out onto its floor, leaving solely SO and newly emitted volcanic SO2 gasoline within the ambiance.
Connection between SO and Volcanoes
“These observations with Webb present for the primary time that the SO truly did come from a volcano,” de Pater mentioned.
De Pater had made earlier observations of Io with the Keck Telescope in Hawaii and located low ranges of the forbidden SO emission over a lot of the moon, however she was unable to tie SO hotspots particularly to an energetic volcano. She suspects that a lot of this SO, in addition to the SO2 seen throughout an eclipse, is coming from so-called stealth volcanoes, which erupt gasoline however not mud, which might make them seen.
Twenty years in the past, de Pater and her workforce proposed that this excited state of SO may solely be produced in scorching volcanic vents, and that the tenuous ambiance allowed this state to stay round lengthy sufficient — just a few seconds — to emit the forbidden line. Usually, excited states that produce this emission are rapidly damped out by collisions with different molecules within the ambiance and by no means seen. Solely in elements of the ambiance the place the gasoline is sparse do such excited states final lengthy sufficient to emit forbidden traces. The greens and reds of Earth’s auroras are produced by forbidden transitions of oxygen within the tenuous higher ambiance.
Additional Observations and Concluding Remarks
“The hyperlink between SO and volcanoes ties in with a speculation we had in 2002 to clarify how we may see SO emission in any respect,” she mentioned. “The one method we may clarify this emission is that if the SO is worked up within the volcanic vent at a temperature of 1500 Kelvin or so, and that it comes out on this excited state, loses its photon inside just a few seconds, and that’s the emission we see. So these observations are the primary that really present that that is the almost certainly mechanism of why we see that SO.”
Webb will observe Io once more in August with NIRSpec. The upcoming statement and the sooner one, which happened on Nov. 15, 2022, had been taken when Io was within the shadow of Jupiter in order that mild mirrored from the planet didn’t overwhelm the sunshine coming from Io.
De Pater famous, too, that the brightening of Loki Patera was in keeping with the noticed interval of eruptions on the volcano, which brighten, on common, about each 500 Earth days, with the brightening lasting for a few months. She decided this as a result of it was not vivid when she noticed the moon with Keck in August and September 2022, nor was it vivid when one other astronomer noticed it from April via July 2022. Solely the JWST captured the occasion.
“The Webb observations confirmed that really eruptions had began, and that it was a lot brighter than what we had seen in September,” she mentioned.
Whereas De Pater is primarily targeted on the Jovian system — its rings, small moons and the bigger moons Ganymede and Io — she and different members of the early science workforce of some 80 astronomers are additionally utilizing JWST to review the planetary techniques of Saturn, Uranus and Neptune.
References:
“Hydrogen peroxide on the poles of Ganymede” by Samantha Okay. Trumbo, Michael E. Brown, Dominique Bockelée-Morvan, Imke de Pater, Thierry Fouchet, Michael H. Wong, Stéphanie Cazaux, Leigh N. Fletcher, Katherine de Kleer, Emmanuel Lellouch, Alessandro Mura, Olivier Poch, Eric Quirico, Pablo Rodriguez-Ovalle, Mark R. Showalter, Matthew S. Tiscareno and Federico Tosi, 21 July 2023, Science Advances.
DOI: 10.1126/sciadv.adg3724
“An Energetic Eruption With Related SO 1.707 Micron Emissions at Io’s Kanehekili Fluctus and a Brightening Occasion at Loki Patera Noticed by JWST” by Imke de Pater, Emmanuel Lellouch, Darrell F. Strobel, Katherine de Kleer, Thierry Fouchet, Michael H. Wong, Bryan J. Holler, John Stansberry, Patrick M. Fry, Michael E. Brown, Dominique Bockelée-Morvan, Samantha Okay. Trumbo, L. N. Fletcher, Matthew M. Hedman, Edward M. Molter, Mark Showalter, Matthew S. Tiscareno, Stéphanie Cazaux, Ricardo Hueso, Statia Luszcz-Prepare dinner, Henrik Melin, Chris Moeckel, Alessandro Mura, Glenn Orton, Lorenz Roth, Joachim Saur, Federico Tosi, 18 July 2023, JGR: Planets.
DOI: 10.1029/2023JE007872
