A group of Japanese astronomers, led by Dr. Haydiki Fujiwara (Hideaki Fujiwara), discovered a main sequence star surrounded by a rare disk of quartz dust. Collisions of planetesimals, the building blocks of planets, can lead to the appearance of the ring of quartz dust around the star during its formation. The opening of the unusual characteristics of the star system, which was done with the help of infrared Spitzer Space Telescope and the AKARI, may encourage scientists to a new study of the mineralogical nature of extrasolar planetary systems.
Since 1995, when it was discovered the first extrasolar planet 51 Pegasi b, astronomers have discovered about 700 planets have a similar type. Understanding the origin and evolution of extrasolar planets has long been one of the topics hotly debated in modern astronomy. A team of scientists led by Dr. Fujiwara tried to look further into this issue, focusing its attention on the detection of fragments in stellar disks, pointing to the formation of planets.
According to a widespread among scientists scenario of planet formation, rocky planets similar to the Earth-type begin their existence as a cluster of cosmic dust, and then continue their development through the accumulation of planetesimals, small solid particles around young stars. A significant amount of dust is likely to emerge as a result of the collision of planetesimals that are around main sequence stars in the later stages of the process of planet formation. Light absorbed by the central star was heated dust particles and debris reproducing their energy as infrared wavelengths. In light of this information, the research team decided to focus its initial research on finding stars with their surrounding disks. To do this, they used a new map of the whole sky in infrared light, which was established on the basis of observations made with AKARI, the Japanese infrared satellite.
For example, scientists have found that sun-like star HD 15407A, located in the constellation Perseus at a distance of 180 light-years from Earth, has issued a very bright infrared light relative to its visible light. Since HD 15407A - is a main-sequence star, active collisions of planetesimals around it could give rise to large amounts of dust and emission of infrared light.
For the observation of a star, astronomers used Spitzer, an infrared space telescope with high sensitivity and sharp resolution, which allowed the identification of the mineralogical nature of the dust and debris. The study of the spectrum of HD 15407A revealed that about 100 trillion tons of small particles of silica dust orbitiruyut star. It was also found that the dust is about 1 AU (astronomical unit) from the central star so-called "area of the planet Earth." This is the first analysis, which not only showed the presence of silica dust in the disk main-sequence stars, but also accurately determine its quantity and distribution in space.
Silica dust is a fairly rare type of dust in the universe, and yet it is not clear how formed silica dust detected around HD 15407A. As the Earth’s crust contains a variety of minerals, quartz-, we can assume that the silica dust got on the disc HD 15407A from the surface layers of large rocky bodies that come into confrontation with the planetesimals orbitiruyuschimi other stars.
Original in (English language): Physorg com