(ORDO NEWS) — Young Jupiter, still hot from its conception, could blast its four largest moons with such intense light that it evaporated water and stripped them of their volatiles.
According to a new study, this radiation could explain why the Galilean moons have such a composition: from the hideous volcano world of Io, closest to Jupiter, to the ice-crusted Europa, then from the giant moon Ganymede to the most distant, cratered Callisto.
These four moons follow two compositional gradients: the farther they move from Jupiter, the lower their density and the higher the proportion of water ice.
Callisto, the solar system’s most cratered body, is about half rock and half ice, while Io has the least ice of any body in the solar system.
A team of astronomers led by planetary scientist Carver Birson of Arizona State University presented their findings at the 54th Moon and Planetary Science Conference.
Astronomers believe that when Jupiter was in the final stages of its formation, it absorbed the last particles of matter from the gaseous disk. and the dust that once surrounded it.
The Galilean moons around Jupiter’s equator are thought to have formed from this disk, like a miniature planetary system.
When the disk dissipated, the newly formed Jupiter shone brightly more than 10,000 times brighter than it is today.
It is still nowhere near as bright as a star, but bright enough that the two innermost Galilean moons, Io and Europa, would be showered with radiation from Jupiter an order of magnitude more intense than the light received from the Sun.
Bierson and his colleagues ran computer simulations to determine the effect this radiation might have. on young moons, suggesting that Io – now the most volcanic body in the solar system – once had a significant amount of water ice after it finished forming.
The team also used Galileo’s current positions of the moons relative to Jupiter, although they were likely closer to the planet billions of years ago.
This means that the amount of radiation they were exposed to was probably higher than in the models found, which could mean that the effects of this radiation manifested more quickly in reality.
“We find,” they write in their conference paper, “that during the first few million years after its formation, Io’s equilibrium temperature may have exceeded 300 kelvins (26.85 degrees Celsius or 80.33 degrees Fahrenheit) due to radiation from Jupiter.
It doesn’t sound very hot it would be a beautiful warm day here on Earth but it would be enough to melt any surface ice, creating sizable oceans, which in turn would create an atmosphere of water vapor.
Even today, Io cannot contain the gases produced by active volcanic activity in its atmosphere.
They rapidly seep into space, feeding on the ring of plasma that surrounds Jupiter, eventually feeding on the gas giant and contributing to its persistent ultraviolet auroras.
Previously, when the moon was first forming, atmospheric ejection would have been the same, spewing water vapor into space, leaving Io more dehydrated than anything else in the solar system.
The impact on Europa would be smaller than that observed on Io, leaving behind enough for a global surface ocean and its thick ice sheet.
Incredibly, today this ocean is a puddle compared to what it once was, and much of its original water has been lost due to Jupiter’s early glow.
Ganymede and Callisto, the Galilean moons farthest from Jupiter, about the same percentage of ice and rock; they would have remained largely unaffected by early irradiation, and any changes between them would have been the result of differences in their subsequent evolution.
The findings, according to Birson and his colleagues, offer a neat and plausible explanation for the strange differences in the composition of the four Galilean moons, which are thought to have formed from the same cloud of dust orbiting Jupiter.
“The unstable stocks we see today on the Galilean satellite could be the result of one strong process, or many acting in concert,” the researchers conclude.
“In this work, we found that the heating of Jupiter could have removed any water supplies on Io in the first few million years, if present…
In general, we show that this process should be taken into account when others try to explain the observed density gradient.”
—
Online:
Contact us: [email protected]
Our Standards, Terms of Use: Standard Terms And Conditions.