Interstellar asteroid different from any seen in our solar system

Up to 10 interstellar asteroids could be traveling through our solar system every year.
By Laurel Kornfeld | Nov 21, 2017
The first asteroid known to have originated beyond our solar system is unlike most asteroids and comets that orbit the Sun, according to astronomers who studied it with the twin Gemini telescopes in Hawaii and Chile.

First observed speeding through the solar system in October by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS 1) in Hawaii, the asteroid, now known as 1I/2017 U1 or 'Oumuamua, was soon recognized as an interstellar object that had been traveling through space for millions of years before entering our solar system.

Recognizing that the object was heading out of the solar system, the discovery team quickly pointed both Gemini telescopes toward it and found it to have a highly elongated shape approximately the size of a football field.

The asteroid was found to rotate very rapidly, about once every 7.4 hours, with dramatic changes in brightness.

Other telescopes around the world, including the Canada-France-Hawaii Telescope (CFHT), the United Kingdom Infrared Telescope (UKIRT), the Keck Telescope on Mauna quickly faded as it headed back to interstellar space.

According to Karen Meech of the University of Hawaii's Institute for Astronomy, leader of the international team studying the asteroid, rapid changes in its brightness indicate it could be ten times longer than it is wide, a feature never seen in solar system objects.

"We observed from both sites (Hawaii and Chile) for three nights, before it sped away and faded from view," noted Gemini director Laura Ferrarese.

Although its shape is unlike anything seen in our solar system, 'Oumuamua shares some characteristics with Kuiper Belt Objects, including a reddish color and composition that may include organic compounds.

Once the object was recognized as having come from beyond our solar system, the International Astronomical Union (IAU) created a new class of objects designated with the letter "I" for interstellar.

Because it was discovered with Pan-STARRS, which is located in Hawaii, the discovery team gave it the Hawaiian name 'Oumuamua, which means "a messenger which reaches out from the distant past."

Our own solar system has likely ejected asteroids and comets as a result of their interactions with the gas giant planets, so it makes sense that the same thing would happen in other solar systems, said research team member Richard Jedicke, who estimates up to 10 interstellar objects per year may traverse the inner solar system.

Findings of the study have been published in the journal Nature.

 

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