Main-belt asteroid shows evidence of March collision

November 18, 2015  |   |  Comments
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Main-belt asteroid (493) Griseldis with temporary tail. Credit: D. Tholen, S. Sheppard, C. Trujillo.

Main-belt asteroid (493) Griseldis with temporary tail. (credit: D. Tholen, S. Sheppard, C. Trujillo)

The main-belt asteroid (493) Griseldis was probably hit by another object last March. So concluded a research group led by University of Hawaiʻi at Mānoa astronomer David Tholen. The results were reported on November 12 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society near Washington, DC.

Observations taken with the 8-meter Subaru Telescope on Maunakea on March 17, 2015 showed that the main-belt asteroid (493) Griseldis had “an extended feature,” which is astronomer-speak for a tail.

However, unlike the tails of comets, which flow in the direction opposite from the sun due to the solar wind, the extension on Griseldis was not in the antisolar direction, and the extension proved to be a short-lived phenomenon.

Additional observations taken with the 6.5-m Magellan telescope four nights later still detected the extension, though it was weaker, but exposures taken with the 2.2-meter UH telescope on March 24 or Magellan on April 18 and May 21 showed no such feature, nor did images from telescope archives taken in 2010 and 2012.

The research group, which also included Scott Sheppard (Carnegie Institution) and Chad Trujillo (Gemini Observatory), has therefore concluded that “the observations are consistent with the occurrence of an impact event on this asteroid.”

The main asteroid belt is located between the orbits of Mars and Jupiter.

An Institute for Astronomy news release

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