Astronomers from the National Astronomical Observatory of Japan (NAOJ) found that a young star in the constellation of the Taurus, DM Tau, that bears a similarity to the sun, has two rings of dust around it, based on data provided by radio-observatory Atacama Large Millimeter/submillimeter Array ALMA. The researchers detected a bright spot on the outer ring - a local concentration of dust that may become the place where a planet the size of Uranus or Neptune may form. This allows us to conclude that we are witnessing the birth of a new planetary system similar to ours
The young star DM Tau is located at the distance of about 470 light years from the Earth. Its age is approximately 3 to 5million years, and its mass is half the mass of the Sun (1,989E30 kg.)
As observations have shown, DM Tau is surrounded by two rings of dust, one of a radius similar to the radius of an asteroid belt (2,8 au - astronomical unit) and the other, of Neptune's orbit (30,06 au).
In the outer ring, in the area more remote from the young star, researchers found a bright spot. It's a concentration of dust that may grow into a planet like Neptune and Uranus. Astronomers are particularly interested in DM Таu's inner ring, as in its time at approximately the same distance from the sun a planet suitable for habitation - the Earth - was formed.
"We are also interested in seeing the details in the inner region of the disk because the Earth formed in such an area around the young Sun. The distribution of dust in the inner ring around DM Tau will provide crucial information to understand the origin of planets like Earth," said Jun Hashimoto, a researcher at the Astrobiology Centre in Japan.
When we talk about the origin of our solar system, the most common and widely accepted is the nebular hypothesis. According to this model, the Sun, the planets and all other celestial bodies of our solar system were formed from dense clouds of molecular hydrogen.
It is believed that the formation of our solar system began about 4.6 billion years ago with a gravitational collapse in the centre of a small part of a giant interstellar molecular cloud. It might have been caused by a passing star or a supernova blast wave. From that moment on, clouds of dust and gas started creating more dense formations. Having reached a certain level of density, the formations, by the law of conservation of momentum, created a ring around this conglomeration.
The central conglomeration eventually turned into the Sun, and the rest of the matter formed a protoplanetary disk. Particles of dust and gas from the matter of this disk gathered into larger bodies, or planets. Near the Sun, only conglomerations with higher concentration of metals and silicates were able to form into denser objects.
Thus formed Mercury, Venus, Earth and Mars. As the presence of metallic elements in the primary solar nebula was weak, these planets weren't capable of significant growth.
In turn, giant planets like Jupiter, Saturn, Uranus and Neptune, were formed beyond the border of negative temperatures, where material freezes to the point where it allows volatile compounds to retain a solid shape in the form of ice.
This allowed the planets to get so huge that with time they created entire atmospheres of hydrogen and helium of their own. The remaining material that wasn't involved in planet formation was concentrated in other regions, eventually forming an Asteroid belt, the Kuiper belt and the Oort cloud.
NAOJ astronomers believe that tg young star DM Tau has every chance of forming a planetary system around itself with planets potentially suitable for birth and sustainment of life.
Besides, astronomers depend on the results of studying young planetary systems to broaden our knowledge of the origin of our own Solar System.