NASA searches for origin of ‘weird’ fast-spinning dwarf planet Haumea
The origins of a dwarf planet lurking at the outer edge of the solar system and becoming one of the strangest objects may have been revealed by NASA scientists.
Dirty is about the size of another dwarf planet Pluto and is located in the Kuiper calls, a collection of icy debris and comets along Neptune’s orbit – the solar systemthe outer planet.
Haumea is notable for spinning faster than any other solar system object of comparable size, completing one rotation around its axis — or a “day” — in just four hours.
This quick spin has led Haumea to develop a shape that resembles a deflated football rather than a sphere. Its shape isn’t the only unusual thing about this dwarf planet, though.
A strange ice mystery
Haumea also has a surface that usually made of some kind of water ice unlike most other bodies in the Kuiper Belt.
This water ice surface is shared by some of Haumea’s siblings who also seem to share the same orbit as the dwarf planet. This has led scientists to conclude that Haumea and these icy bodies have the same origin and that they form the only “family” of related objects found in the Kuiper belt – the “Haumean family.”
Using computer simulations, NASA scientists have included: Goddard Space Flight Center in Greenbelt, Maryland, postgraduate student Jessica Noviello explored the question “How did something as weird as Haumea and his family come to be?”
Computer simulations are needed to achieve this, as the dwarf planet is too far away to measure accurately with an Earth-based telescope, and Haumea has yet to be visited by a space mission.
These simulations allowed the team to “take apart” Haumea and then rebuild it from scratch. The purpose of this was to understand the chemical and physical processes that shaped the dwarf planet.
“To explain what happened to Haumea, we need to put time limits on all these things that happened when the solar system was forming, so that it starts connecting everything in the solar system,” team member and Arizona State University in Tempe, professor of astrophysics, said Steve Desch in a pronunciation. “There are a lot of weird, ‘gee-wizz’ parts in Haumea, and it was a challenge to explain them all at once.”
The model developed by the team started with the input of only three data about Haumea; its estimated size, its estimated mass and its short “day” of four hours.
This provided a revised prediction of the dwarf planet’s size and mass and its density. It also provided a prediction of Haumea’s core size and density.
Using this information, Noviello was able to determine how the dwarf planet’s mass is distributed and how that distribution affected its spin. From here, the researcher began simulating billions of years of evolution for Haumea in search of the right set of features that would result in the dwarf planet astronomers observe today.
“We wanted to fundamentally understand Haumea before going back in time,” said Noviello.
Haumea family values
The team assumed Baby Haumea was about 3% larger than its current size, with the difference explaining the creation of its Kuiper Belt siblings.
The scientists also assumed that the young dwarf planet orbited at a different speed and that its volume was greater than it is now.
By adjusting Haumea’s features in the models they developed, the team was able to run dozens of simulations to see how small changes, such as the size of the dwarf planet, changed its evolution.
Arriving at a model that yielded a simulated Haumea, exactly as astronomers observe today, the team said they had found the correct early features and current evolutionary path for the dwarf planet in the Kuiper Belt.
Noviello and her colleagues’ modeling revealed that in the early years and during an era of the solar system characterized by chaotic conditions, Haumea collided with another body with a powerful impact.
This resulted in pieces coming loose from the young Haumea, but these fragments did not become the Haumean family objects. This is because such a large impact would have smashed the pieces into much more dispersed orbits than those of the Haumean family’s bodies.
Desch said the objects that make up the Haumean family would likely have formed later in the dwarf planet’s existence as the structure evolved. In this later period of its evolution, dense, rocky material sank toward the center of the dwarf planet, while lighter-density ice rose toward the surface.
“When you concentrate all the mass towards the axis, it reduces the moment of inertia, so Haumea ended up spinning even faster than today,” Desch said. This would result in rotational speeds fast enough to shed surface ice, which would later become the Haumean family.
This moment of inertia would have increased further, decreasing the spin rate of the dwarf planet due to radioactivity from the rocks of Haumea’s melting surface ice. This water soaked to the center of the dwarf planet caused rocky material there to swell into a large but less dense clay core.
The team’s research was published in the Planetary Science Journal on September 29.
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