On a small dwarf planet called Makemake, astronomers have seen signs of surprising temperature changes. These could indicate that the tiny world, which is about 45 times further from the sun than Earth, has an active icy volcano.
at Konkoly Observatory in Hungary and his colleagues used the James Webb Space Telescope (JWST) to study Makemake for less than an hour. They observed a spike in infrared light that corresponded to a temperature of -120°C (-184°F), far above Makemake’s average temperature of -240°C (-400°F).
“It’s very unusual,” says Kiss. “We’ve identified two possible scenarios that could explain this. One is an active cryovolcano. The other is very fine-grained dust around Makemake.”
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Makemake is located in the Kuiper Belt, a region of icy objects beyond Neptune where Pluto also resides. When the New Horizons spacecraft flew past Pluto in 2015, it was shown to have evidence of past cryovolcanic activity – the cold eruption of liquid or gas from the surface.
An infrared spike on Makemake was also spotted by NASA’s Spitzer space telescope 20 years ago, but no temperature measurement could be made without the increased sensitivity of JWST.
If the spike is caused by cryovolcanic activity, it might be an ongoing eruption from an ocean that has been kept liquid by latent heat inside the dwarf planet from its formation. Earlier this year, separate work using JWST found hints of such in the dwarf planet.
“It’s probably not pure water” that is erupting, says Kiss. He says it probably contains salts of ammonia, magnesium and other substances. Even if it is a cryovolcano, it may not look like one to an observer on the surface. “It could even be methane blowing out from holes or cracks,” he says.
But the spike could also be caused by fine-grained dust in a ring around Makemake being heated by the sun. “A large amount of these very small grains could explain the high temperature we see,” says Kiss. It might even be due to both processes linked together, with cryovolcanism firing fine-grained material into space.
To find out, JWST would need to observe the dwarf planet for longer and see if the spike increases or decreases as the dwarf planet, and any accompanying surface cryovolcanism, rotates in and out of view during the course of a day on Makemake.
“Both scenarios are special,” says Kiss. “We have never seen fine-grained discs around these objects. And it’s absolutely unique to see an active cryovolcano in the Kuiper Belt.”
Reference:
arXiv
