June 7th, 2013 by James Ayre
The 2011 Draconid meteor shower deposited over a ton of meteoritic material onto the Earth, according to new research from the CSIC Institute of Space Sciences. The material of course can be traced back to comet 21P/Giacobini-Zinner — whose debris trail is what powers the Draconid meteor shower, which occurs annually around October 8-9.
The 2011 Draconids were one of the most prolific meteor showers of recent years, peaking at about 400 meteors per hour.
The comet Giacobini-Zinner makes its way through the inner solar system, roughly, every 6.6 years. During that periodic journey, the comet’s ices sublimate and large qualities of particles that were previously distributed in filaments are released. “The oldest of these particles have formed a swarm that Earth passes trough every year in early October. The result is a Draconid meteor shower — meteors from this comet come from the northern constellation Draco — which hits Earth’s atmosphere at about 75,000 km/h, a relatively slow speed in comparison with other meteoric swarms.”
Josep Maria Trigo, researcher from the CSIC Institute of Space Sciences (ICE), says: “When a comet approaches the Sun, it sublimates part of its superficial ice and the gas pressure drives a huge number of particles that adopt orbits around the Sun, forming authentic swarms. The study shows that in the evening from October 8th to 9th 2011, the Earth intercepted three dense spindles of particles left behind by the comet when it crossed through the perihelion.”
The researchers were able to confirm the origin of these particles with the aid of “25 video-detection stations operated by the Spanish Meteor and Firewall Network (SPMN) and the collaboration of amateur astronomers. Two of those filaments of meteoroids, which had been theoretically predicted already, have been identified by scientists with those left by the comet in 1874, 1894 and 1900. Nevertheless, researchers have confirmed that there was another dense region intercepted by Earth which had not been predicted and that involves a new challenge for theoretical models.”
In related research, the chemical composition of six of the fireballs associated with the 2011 Draconids were recently analyzed. José María Madiedo, researcher from the University of Huelva and coordinator of this second study, states: “One of them, with an initial mass of 6 kg and nearly half a meter in diameter, named Lebrija in honor of the city it over flew, came to compete with the brightness of the moon that night.”
“The six analyzed fragments have a possibly similar composition to the carbonaceous chondrites (a type of organic-rich meteorites) but they are much more fragile.” Trigo emphasizes: “They don’t seem to have suffered any chemical alteration during their brief stay in the interplanetary environment, which turns out to be very interesting to confirm the astrobiological role of these particles in the continuous transportation of water and organic material to the Earth.”
The new research was recently published in the Monthly Notices of the Royal Astronomical Society magazine.
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