June 11 (UPI) -- Ahuna Mons, the tallest mountain on the dwarf planet Ceres, is made of volcanic mud, according to new analysis of data collected by the spacecraft Dawn.
As observations by NASA's Dawn spacecraft first revealed in 2015, Ahuna Mons looks a lot like a volcano. Its shape recalls a mini volcanic dome, and the bright, salty streaks running down its slopes look a lot like the streaks of magma that flow down the sides of volcanoes on Earth.
Despite the visual evidence, scientists were skeptical of Ceres' volcanism. Dwarf planets like Ceres cooled relatively quickly after their formation. And because they're so small and cold, scientists thought their formation process left little room in the interior for volcanic activity.
But new analysis of Dawn data has confirmed scientists' suspicisions that Ceres is an anomaly.
First, the mountain's slopes feature relatively few craters. Though scientists estimate Ceres is at least 4.5 billion years old, the dome's smooth surface suggests Ahuna Mons is only a few million years old.
When researchers took a fresh look at gravity data collected by Dawn, they found evidence of a plume running beneath Ahuna Mons. The new findings -- published this week in the journal Nature Geoscience -- suggest the plume contains a slushy like mixture of salty brine and solid particles.
"This structure is the probable source of fluids forming Ahuna Mons," researchers wrote in their new paper. "We propose that the properties of such a solid-liquid mixture can explain the viscous relaxation and the mineralogy of the dome."
According to the authors of the new paper -- a mix of planetary scientists from the United States and Europe -- the plume and resulting dome is unlike any documented so far in the solar system.
"The inferred slurry extrusion on Ceres differs from the water-dominated cryovolcanism of icy satellites, and so reveals compositional and rheological diversity in extrusive phenomena on planetary surfaces," researchers wrote.