A group of Finnish astronomers from the University of Helsinki have studied for the first time the composition of the asteroid Phaethon, which causes meteor showers in the skies above Earth every year. The study was published in the scientific journal magazine Nature Astronomy (NatAstro).
Asteroid Phaeton, five kilometers in diameter, has long puzzled scientists. When a celestial body approaches the Sun, it develops a tail similar to the tails of comets. When the space object’s surface layer breaks apart, the separated dust and gravel continue in the same orbit and, when they meet Earth, cause the Geminid meteor shower in mid-December.
Finnish researchers examined the infrared spectrum of Phaeton, previously measured by the Spitzer Space Telescope, and compared it with the spectra of other meteorites.
The analysis showed that Phaeton’s spectrum closely matched that of a very rare type of meteorite known as a CY carbonaceous chondrite. Today astronomers know of only six such objects.
Phaeton contains olivine, carbonates, iron sulphides and oxide minerals. Carbonates show changes in water content, while olivine shows thermal decomposition of layered silicates at extreme temperatures.
According to the research, all of the minerals detected in Phaethon correspond to the minerals in CY type meteorites. The only exceptions were portlandite and brucite oxides, which are not found in meteorites. However, these minerals can be formed by heating and disintegrating carbonates in the presence of water vapor.
Scientists used experimental data from other studies along with their thermal models to calculate that during an asteroid’s closest pass to the Sun, gas would be released from the asteroid’s mineral structure that could cause rock to fracture.
Additionally, the pressure created by carbon dioxide and water vapor is high enough to lift fine dust particles from the asteroid’s surface.
“Sodium emissions could explain the faint tail we see near the Sun, and thermal weathering could explain how dust and gravel are expelled from Phaeton,” said Eric McLennan, lead author of the study.
Earlier astronomers discovered An asteroid in the solar system that contains elements not included in the periodic table.