February 21, 2013
Astronomers Gain Understanding Of Asteroid Trail
Lee Rannals for redOrbit.com — Your Universe Online
Astronomers writing in The Astrophysical Journal Letters say they have discovered the reason behind the strange scene when finding an asteroid with a tail.
Just ten asteroids to date have been observed to have displayed a tail, similar to a comet, and one of these objects, P/2012 F5, was discovered in March 2012 from the Mount Lemmon Observatory in Arizona. These asteroids are also known as MBCs.
Spanish astrophysicists from the Gran Telescopio Canarias tracked and discovered where the tail was born using mathematical calculations.
"Our models indicate that it was caused by an impulsive short-lived event lasting just a few hours around the 1st July, 2011, with an uncertainty of 20 days," said Fernando Moreno, researcher at the Astrophysics Institute of Andalusia (CSIC).
The telescope revealed a fine and elongated dust structure, coinciding with exactly the synchronicity of that day, according to the researchers. A synchronicity is the position in the sky of the particle emitted from these types of objects with zero speed in an instant of time.
Researchers working on the project struggled with two possible theories for the origin of the P/2012 F5 tail.
"It could have arisen from collision with another asteroid or rather a rotational rupture," the authors said. The second mechanism, according to the researchers, consists of material gradually breaking free after partial fragmentation of the asteroid.
Moreno says they have verified the dependence of the speed of particle ejection on size is very weak, according to what they had already obtained for the other asteroid of this group.
MBCs are main-belt asteroids situated at a distance of between two and 3.2 astronomical units, which is the average distance between the Earth and the Sun. These asteroids become active and emit dust, however they have not been found to generate gas due to the fact they are weak at the moment of observation. Since discovery of the first MBC in 1996, a total of ten have been found.
The presence of a tail in some has lasted for a relatively long period of a few months, like in the cases of 2006 VW139, and P/2010 R2. The latter was discovered from an observatory of the same name in Granada. In the case of (596) Scheila, it had activity develop during a short period of time and its dust cloud dissipated very quickly in a matter of three or four weeks. Other examples of MBCs have shown recurrent activity, such as 133P/Elst-Pizarro and 238P.
The skies have been full of asteroid activity recently, including 2012 DA14, which passed by Earth February 15 at just a little over 17,000 miles away. The 150-foot diameter asteroid was closer to Earth than our own weather and television satellites.
The morning of DA14 passing by Earth, a large meteor pounded Earth with the force of nearly 500 kilotons of TNT, which is about 30 times the energy released by the Hiroshima atomic bomb. The Earth will come into contact with an asteroid with this magnitude once every several tens to 100 years, according to the European Space Agency.