Release 116 of 1,157

Hubble Takes Close-up Look at Disintegrating Comet

Release date: Sep 15, 2016 1:00 PM (EDT)
Hubble Takes Close-up Look at Disintegrating Comet

Comet 332P/Ikeya-Murakami survived for 4.5 billion years in the frigid Kuiper Belt, a vast reservoir of icy bodies on the outskirts of our solar system. The objects are the leftovers from our solar system's construction. But within the last few million years, the unlucky comet was gravitationally kicked to the inner solar system by the outer planets. The comet, dubbed 332P, found a new home, settling into an orbit just beyond Mars. But the new home, closer to the sun, has doomed the comet. Sunlight is heating up Comet 332P's surface, causing jets of gas and dust to erupt. The jets act like rocket engines, spinning up the comet's rotation. The faster spin rate loosened chunks of material, which are drifting off the surface and into space.

The Hubble Space Telescope caught the latest cloud of debris ejected by Comet 332P. The images, taken over three days in January 2016, represent one of the sharpest, most detailed observations of a comet breaking apart. Hubble reveals about 25 building-size chunks from the comet floating through space at roughly the walking speed of an adult. Material will continue to break away from Comet 332P. Astronomers estimate that the comet, which has survived for 4.5 billion years, will be gone in another 150 years.

The Full Story
Release date: Sep 15, 2016
Hubble Takes Close-up Look at Disintegrating Comet





"We know that comets sometimes disintegrate, but we don't know much about why or how they come apart," explained lead researcher David Jewitt of the University of California at Los Angeles. "The trouble is that it happens quickly and without warning, and so we don't have much chance to get useful data. With Hubble's fantastic resolution, not only do we see really tiny, faint bits of the comet, but we can watch them change from day to day. And that has allowed us to make the best measurements ever obtained on such an object."





The research team calculated that the comet probably shed material over several months, between October and December 2015. Jewitt suggests that even some of the ejected pieces have themselves fallen to bits in a kind of cascading fragmentation. "Our analysis shows that the smaller fragments are not as abundant as one might expect based on the number of bigger chunks," he said. "This is suggestive that they're being depleted even in the few months since they were launched from the primary body. We think these little guys have a short lifetime."

Hubble's sharp vision also spied a chunk of material close to the comet, which may be the first salvo of another outburst. The remnant from still another flare-up, which may have occurred in 2012, is also visible. The fragment may be as large as Comet 332P, suggesting the comet split in two. But the icy remnant wasn't spotted until Dec. 31, 2015, by the Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) telescope in Hawaii, in work supported by the Near-Earth Object Observations program in NASA's Planetary Defense Coordination Office. That discovery prompted Jewitt and colleagues to request Hubble time to look at the comet in detail. Around the same time, astronomers around the world began to notice a cloudy patch of material near the comet, which Hubble later resolved into the 25 pieces.

"In the past, astronomers thought that comets die when they are warmed by sunlight, causing their ices to simply vaporize away," Jewitt said. "Either nothing would be left over or there would be a dead hulk of material where an active comet used to be. But it's starting to look like fragmentation may be more important. In Comet 332P we may be seeing a comet fragmenting itself into oblivion."

"Hubble's best previous glimpse at a fragmenting comet came during Advanced Camera for Surveys (ACS) observations of 73P/Schwassmann-Wachmann 3 (73P) in April 2006," said collaborator Harold Weaver of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. "In those observations, Hubble witnessed a comet with more than 60 named pieces. The Hubble images showed unprecedented detail of 73P's breakup, but the comet wasn't observed long enough to document the evolution of the fragments over time, unlike the case of 332P."

The researchers estimate that Comet 332P contains enough mass to endure another 25 outbursts. "If the comet has an episode every six years, the equivalent of one orbit around the sun, then it will be gone in 150 years," Jewitt said. "It's the blink of an eye, astronomically speaking. The trip to the inner solar system has doomed it."

The icy visitor hails from the Kuiper Belt, a vast swarm of objects at the outskirts of our solar system. These icy relics are the leftover building blocks from our solar system's construction. After nearly 4.5 billion years in this icy deep freeze, chaotic gravitational perturbations from Neptune kicked Comet 332P out of the Kuiper Belt.

As the comet traveled across the solar system, it was deflected by the planets, like a ball bouncing around in a pinball machine, until Jupiter's gravity set its current orbit. Jewitt estimates that a comet from the Kuiper Belt gets tossed into the inner solar system every 40 to 100 years.

