A work led by researchers from the Higher Council for Scientific Research (CSIC) has revealed thatabout a ton of material from comet 21P / Giacobini-Zinner was deposited in the Earth’s atmosphere on October 8 and 9, 2011, during one of the most intense falling star showers of the last decade, which recorded an activity of just over 400 meteors per hour.
Every 6.6 years, Comet Giacobini-Zinner circulates through the inner solar system and passes through perihelion, the point closest to the Sun in its orbit. At that time, the comet sublimates part of the surface ice and ejects a large number of particles that are distributed in filaments around the star. Of them, the oldest have formed a swarm that the Earth transits each year at the beginning of October. The result is theDraconid meteor shower, hitting Earth’s atmosphere at about 75,000 kilometers per hour, a relatively slow speed compared to other meteor swarms.
“The study shows that the evening from October 8 to 9, 2011 the Earth intercepted three dense spindles of particles left by the comet as it passed through perihelion”, explains the CSIC researcher at the Institute of Space Sciences Josep María Trigo, who has announced her results in the magazineMonthly Notices of the Royal Astronomical Society. Scientists obtained the orbits in the solar system of about twenty meteors with 25 videodetection stations operated by the Research Network on Bolides and Meteorites, with the collaboration of amateur astronomers.
In a second article, the researchers analyze thechemical compositionfromsix fireballs from that comet swarm recorded during the outburst. “One of them, with an initial mass of six kilograms and almost half a meter in diameter, called Lebrija in honor of the Andalusian city that it flew over, came to rival the brightness of the Moon that night,” says José María Madiedo, researcher at the University of Huelva and coordinator of this second work.
The six fragments analyzed have a composition possibly similar to thecondritas carbonáceas(a type of meteorites rich in organic matter), but they are much more fragile. “They do not seem to have undergone chemical alteration in their brief stay in the interplanetary environment, something that is very interesting to corroborate the astrobiological role of these particles in the continuous transport of water and organic matter to Earth”, highlights Trigo.
