With the help of the Hubble Space Telescope, an international research team has observed an unusual pair of space rocks in the asteroid belt between Mars and Jupiter. This binary asteroid, labled 2006 VW139/288P, is the first known binary asteroid also classified as a comet.
According to the research, published this week in the journal Nature, the two asteroids, collectively called 288P, orbiting each other and showing also comet-like features, including a bright halo of material, called a coma, and a long tail of dust.
Using the Hubble Space Telescope, a project of international cooperation between the US National Aeronautics and Space Administration (NASA) and European Space Agency (ESA), astronomers observed the asteroid pair last September just before it made its closest approach to the sun.
The images of the asteroid 288P revealed that it was actually not a single object, but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. The German-led group concluded that 288P has existed as a binary system for only about 5,000 years.
"The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the two fragments may have been moved further apart by sublimation torques," Jessica Agarwal, lead author of the paper elaborated on the formation scenario in a press release.
Understanding the origin and evolution of main-belt comets, asteroids orbiting between Mars and Jupiter that show comet-like activity, is a crucial element in our understanding of the formation and evolution of the whole solar system, the scientists said in a statement.
The binary asteroids' strange characteristics raises some questions about whether it is not just a coincidence that it presents such unique properties.
"We need more theoretical and observational work, as well as more objects similar to 288P, to find an answer to this question," concludes Agarwal.