A Bright Halo of Material

  • An unusual object, discovered in the solar system’s asteroid belt, is actually two asteroids orbiting each other, scientists including one of Indian origin have found using the Hubble Space Telescope.
  • The object has comet-like features including a bright halo of material, called a coma, and a long tail of dust.
  • Hubble was used to image the asteroid, designated 300163 (2006 VW139), in September 2016 just before the asteroid made its closest approach to the Sun.
  • The images revealed that it was actually not one, but two asteroids of almost the same mass and size, orbiting each other at a distance of 96 kilometres.
  • Asteroid 300163 (2006 VW139) was discovered by Spacewatch in November 2006 and then the possible cometary activity was seen in November 2011 by Pan – STARRS.
  • Both Spacewatch and Pan-STARRS are asteroid survey projects of NASA’s Near Earth Object Observations Program.
  • After the Pan-STARRS observations it was also given a comet designation of 288P.
  • This makes the object the first known binary asteroid that is also classified as a main-belt comet. 
  • The more recent Hubble observations revealed ongoing activity in the binary system.
  • The combined features of the binary asteroid – wide separation, near-equal component size, high eccentricity orbit, and comet – like activity- also make it unique among the few known binary asteroids that have a wide separation.
  • Understanding its origin and evolution may provide new insights into the early days of the solar system. 
  • Main-belt comets may help to answer how water came to a bone-dry Earth billions of years ago.

About Binary Asteroid System

  • The team estimates that 2006 VW139/288P has existed as a binary system only for about 5,000 years.
  • The most probable formation scenario is a breakup due to fast rotation.
  • After that, the two fragments may have been moved further apart by the effects of ice sublimation, which would give a tiny push to an asteroid in one direction as water molecules are ejected in the other direction.
  • The fact that 2006 VW139/288P is so different from all other known binary asteroids raises some questions about how common such systems are in the asteroid belt.
  • We need more theoretical and observational work, as well as more objects similar to this object, to find an answer to this question.

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