P/2010 A2 Was An Asteroid Collision (Says Hubble)

What you see here is something mankind has never seen before, the aftermath of an asteroid collision. This conclusion comes after the Hubble Space Telescope was commanded to take a closer look at a strange comet-like object pottering around in the asteroid belt between the orbits of Mars and Jupiter.

The truth is we’re still struggling to understand what this means,” said David Jewitt, a planetary physicist from UCLA. “It’s most likely the result of a recent collision between two asteroids.”

After P/2010 A2 was discovered in January, Jewitt managed to get observation time on Hubble to get a closer look of what was thought could be a rare asteroid-comet hybrid.

In the image, the object named P/2010 A2 has a very obvious “X” on its surface shaped pattern in its tale, possibly the location where a smaller body slammed into it at high speed. The result of this hyper-velocity impact produced a lot of debris and scientists think the comet-like tail being swept back by the pressure of the solar wind is dust and outgassing volatiles (like subliming water ice).

Although this kind of event has never been observed before, over the lifetime of the evolving solar system, events like this occur on a regular basis, in fact asteroid collisions have shaped the asteroid belt. Interestingly, it is thought this impact was caused by a collision of a “Flora family” asteroid, a type of object that may have wiped out the dinosaurs 65 million years ago. (Don’t worry, this collision won’t affect Earth in any way, the dinosaur thing is simply an interesting connection!)

What an incredible discovery, it’s fortunate that we have Hubble’s excellent eyesight to peer deep into the asteroid belt…

Sources: Reuters, Discovery News

Could P/2010 A2 be the First Ever Observation of an Asteroid Collision?

Something rather bizarre was observed in the asteroid belt on January 6. Ray Villard at Discovery News has just posted an exciting article about the discovery of a comet… but it’s not your average, run-of-the-mill kinda comet. This comet appears to orbit the Sun, embedded in the asteroid belt.

Comets don’t usually do that, they tend to have elliptical and inclined orbits, orbits that carry them close to the Sun (when they start to heat up, creating an attractive cometary tail as volatile ices sublimate into space, producing a dusty vapor). They are then flung back out into the furthest reaches of the Solar System where the heating stops and the comet tail disappears until the next solar approach.

But P/2010 A2 — discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey — has a circular orbit and it still appears to be venting something into space.

P/2010 A2 (LINEAR): A comet or asteroid debris? (Spacewatch/U of Arizona)

There is the possibility that it is a member of a very exclusive bunch of objects known as main belt comets (MBCs). MBCs are confused asteroid/comet hybrids that appear to spontaneously vent vapor and dust into space and yet stay confined to the asteroid belt. But, if P/2010 A2 is confirmed to be one of these, it will only be the fifth such object to be discovered.

So what else could it be? If the potential discovery of an MBC doesn’t excite you enough, it could be something else entirely: the dust produced by a hyper-velocity impact between two asteroids. If this is the case, it would be the first ever observation of an asteroid impact in the Solar System.

The asteroid belt isn’t the same asteroid belt you might see in science fiction; although there are countless rocky bodies in our asteroid belt, it is rare that these rocky bodies encounter each other. Space is very big, and although the density of asteroids in this region might be considered to be “high”, this is space we’re talking about, you can fly a spaceship through the region without having to worry that you’ll bump into something. The average distance between asteroids is huge, making it a very rare occurrence any two should hit. But given enough asteroids, and enough time, eventually asteroid collisions do happen. And in the case of P/2010 A2, we might have been lucky.

Asteroid collisions: Rare, but possible.

Asteroid collisions: Rare, but possible.

The chatter between comet/asteroid experts is increasing, and on one message board posting, Javier Licandro (Instituto de Astrofísica de Canarias, Spain) reports observing a secondary asteroid traveling with the cloud-like P/2010 A2.

The asteroid moves in the same direction and at the same rate as the comet,” reports Licandro on The Minor Planet Mailing List. “In addition, the P/2010 A2 (LINEAR) image does not show any central condensation and looks like a ‘dust swarm’.”

A short lived event, such as a collision, may have produced the observed dust ejecta.”

Therefore, this ‘comet’ may actually be the debris that was ejected after a collision between two asteroids. Although these are preliminary findings and it’s going to take some serious observing time to understand the true nature of P/2010 A2, it’s exciting to think that we may just have observed an incredibly rare event, 250 million miles away.

Source: Discovery News