[meteorite-list] Main-Belt Asteroid 493 Griseldi Shows Evidence of March Collision

[Ron Baalke]

http://www.ifa.hawaii.edu/info/press-releases/493Griseldis/

Main-Belt Asteroid Shows Evidence of March Collision
University of Hawaii

For release on November 12, 2015 at 12 noon EST (7 a.m. HST)

Contacts:

Dr. David Tholen
tholen at ifa.hawaii.edu

Dr. Roy Gal
Media Contact
+1 808-956-6235
cell: +1 301-728-8637
rgal at ifa.hawaii.edu
 

[Image]
Image of main-belt asteroid (493) Griseldis with temporary tail taken 
with the Subaru Telescope on Maunakea. Credit: D. Tholen, S. Sheppard, 
C. Trujillo.

The main-belt asteroid (493) Griseldis was probably hit by another object 
last March. 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 17 
March 2015 UT 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 University of Hawaii telescope on 24 March UT 
or Magellan on 18 April UT and 21 May UT showed no such feature, nor did 
images from telescope archives taken in 2010 and 2012.

The researchers, David Tholen (Institute for Astronomy, University of 
Hawaii at Manoa), Scott Sheppard (Carnegie Institution) and Chad Trujillo 
(Gemini Observatory) have 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.

Illustrations

Uncropped Subaru image (same as above image)

Four-panel image: The top three panels are three different exposures with 
Subaru with asteroid (493) Griseldis moving from left to right as you 
move from the first panel to the third one. The bottom panel shows all 
three exposures added together, after suppressing the galaxy that interferes 
with the "tail" in the first exposure; the asteroid is on the right. Credit: 
D. Tholen, S. Sheppard, C. Trujillo.       72 dpi       300 dpi

Image taken with the Magellan Telescope in Chile four days later shows 
a reduced "tail." Credit: S. Sheppard.

Founded in 1967, the Institute for Astronomy at the University of Hawaii 
at Manoa conducts research into galaxies, cosmology, stars, planets, and 
the sun. Its faculty and staff are also involved in astronomy education, 
deep space missions, and in the development and management of the observatories 
on Haleakala and Maunakea. The Institute operates facilities on the islands 
of Oahu, Maui, and Hawaii.