Astronomers Puzzle Over Newfound Asteroid That Acts Like a Comet [Online video]
PIECING IT Together: 4 apparent fragments of primary-belt comet P/2013 R3 are highlighted in this picture from the Gran Telescopio Canarias. A few are clustered in close proximity to the head of the comet (inset), and a fourth was discovered in the tail (circled).
The distinction between comets and asteroids is in principle a distinct one, encoded proper in the words and phrases them selves. Each conditions appear from Greek roots—“comet” descends from a word indicating “long-haired” and “asteroid” indicates, around, “starlike.” So there it is: comets are fuzzy, and asteroids are discrete pinpricks of light-weight. The definitions hint at compositional variations as effectively: comets are icy, which leads them to occur aside when they draw around the sun, while rocky asteroids are somewhat more sturdy.
In current several years, even though, astronomers have noticed that asteroids can suddenly don the appearance of comets, comprehensive with a fuzzy head and a lengthy tail. Astronomers call them major-belt comets, simply because they show cometlike qualities but orbit inside the Asteroid Belt in between Mars and Jupiter. (Comets originate from far more distant realms in the outer solar technique.)
The explanations set forth for how an asteroid masquerades as a comet normally entail some form of disruption, this kind of as a more compact item colliding with the asteroid and ejecting a cloud of particles or the partial disintegration of the asteroid as daylight vaporizes pockets of ice in. A newfound main-belt comet, nevertheless, looks fairly a little bit various than the rest. Astronomers have nevertheless to make clear its features, which include not just a tail but a cluster of fragments exactly where a single head need to be. “Even in the wild spectrum of principal-belt comets, this 1 is uncommon,” states astronomer David Jewitt of the University of California, Los Angeles. “There are certainly no excellent theories out there for what we’re searching at.”
The principal-belt comet, specified P/2013 R3, was discovered in September at two observatories: the Catalina Sky Survey in Arizona and the Pan-STARRS 1 telescope in Hawaii. Only a dozen or so main-belt comets have been uncovered, so astronomers speedily took to the world’s greatest telescopes to get a better look at the uncommon item. Jewitt examined P/2013 R3 with the 10-meter Keck one telescope in Hawaii, whilst astrophysicist Javier Licandro of the Institute of Astrophysics of the Canary Islands and his colleagues used the institution’s 10.four-meter Gran Telescopio Canarias. Equally observed that the object was various than all other major-belt comets identified so far. “What we noticed is that the item is not a single nucleus with a tail,” Licandro suggests. He and his colleagues have determined four distinct pieces: two in close proximity to the major, vivid nucleus and an additional in the tail. “It is the first time that one particular of these principal-belt comets is discovered that has split in parts,” he states.
There might be more fragments waiting around to be identified, which is why Jewitt and his colleagues have secured time on the Hubble Area Telescope to get a clearer check out. “We see three or 4 parts from the floor, but who knows what we will see with the HST?” Jewitt says.
The Hubble observations may possibly also support clarify just what occurred in the modern earlier to flip an undistinguished asteroid into a primary-belt comet. Jewitt says that his preliminary data from Keck unveiled that P/2013 R3 appeared much like a break up comet, or a comet that has broken into several parts. The regular clarification for break up comets is the sublimation of a comet’s ice directly to vapor, which spews out fuel and dust to sort the fuzzy head and tail of a typical comet but can often blow out a massive chunk of a comet’s nucleus as effectively. “The thriller is, however, that this object is not losing that considerably mass. It is relatively faint,” Jewitt adds. “It’s a tiny little bit difficult to say why the sublimation would break up the nucleus like that.”