Asteroid Is Actually A Protoplanet
Britney E. Schmidt, a UCLA doctoral student in the department of Earth and space sciences, wasn't sure what she'd glean from images of the asteroid Pallas taken by the Hubble Space Telescope.
But she hoped to settle at least one burning question: Was Pallas, the second-largest asteroid, actually in that gray area between an asteroid and a small planet?
The answer, she found, was yes. Pallas, like its sister asteroids Ceres and Vesta, was that rare thing: an intact protoplanet.
"It was incredibly exciting to have this new perspective on an object that is really interesting and hadn't been observed by Hubble at high resolution," Schmidt said of the first high-resolution images of Pallas, which is believed to have been intact since its formation, most likely within a few million years of the birth of our solar system.
"We were trying to understand not only the object, but how the solar system formed," Schmidt said. "We think of these large asteroids not only as the building blocks of planets but as a chance to look at planet formation frozen in time."
The research appears Oct. 9 in the journal Science.
"To have the chance to use Hubble at all, and to see those images come back and understand automatically this could change what we think about this object - that was incredibly exciting to me," Schmidt said.
Pallas, which is named for the Greek goddess Pallas Athena, lies in the main asteroid belt between the orbits of Jupiter and Mars. Schmidt likens it to the size of Arizona, her home state. The massive body is unique, she said, partly because "its orbit is so much different from other asteroids. It's highly inclined."
Hubble had tried to snap pictures of the round-shaped body before but came up short. So when the space telescope took images again in September 2007, Schmidt and her colleagues had several goals.
"We wanted to learn about Pallas itself - what its shape is like, what its surface is like, does it have large impact craters, does it have significant topography," she said.
"Pallas's largest crater-like feature seen in the digital model (left) and from two perspectives: appearing face-on (upper right) and edge-on along the limb (lower right). (Credit: This image is courtesy of Science/AAAS in a paper by Britney Schmidt, et al.)"
Source: University of California - Los Angeles
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