The study was published in Astronomy & Astrophysics, where the discovery is described.
In the study, astronomers suggested that even if the stars were close to death, some of them could still form planets. If this is confirmed, theories about planet formation will need to be adapted.
Planets like Earth and all the other planets in our solar system were born soon after the Sun. Our sun began to burn 4.6 billion years ago, and over the next million years, the matter around it clumped into protoplanets. The birth of planets in a protoplanetary disk, so to speak, a giant pancake made of dust and gas with the sun in the middle, explains why they all orbit the same plane.
But such dust and gas wafers don’t necessarily have to surround only newborn stars. They can also evolve independently of the formation of stars, for example around a twin star, one of which is dying (twin stars are two orbiting stars, also called a dual system). As the end of a medium-sized star (such as the Sun) approaches, it catapultes into the outer space of the atmosphere, after which it dies slowly in the so-called as a white dwarf.
However, in the case of binary stars, the attraction of the second star causes the substance ejected by the dying star to form a flat, rotating disk. In addition, this disk strongly resembled the protoplanetary plates observed by astronomers around young stars elsewhere on the Milky Way.
This was a fact already known. What is new, however, is that there are no rare signs in the disks surrounding the so-called advanced double stars that could indicate the formation of planets, as observed by an international group of astronomers led by KU Leuven scientists.
In addition, their findings showed that this is the case for every tenth of these double stars. “In ten percent of the evolved binary stars with the disks we study, we see a large cavity (vacuum / gap, ed.) In the plate,” says the astronomer at KU Leuven. Jacques Kluska, the first author of the study. “This is a sign that something is floating there that has collected all the matter from the area of the cavity.”
Cleaning it up could be the job of the planet. This planet may not have formed at the beginning of the life of one double star, but at the very end. In addition, astronomers found strong indications of the existence of such planets.
“In the advanced twin stars with a large cavity in the plate, we saw that there were very few heavy elements, such as iron, on the surface of the dying star,” Kluska said. “This finding raises the suspicion that dust particles containing these elements were trapped on the planet.” Incidentally, the astronomer of Leuven did not rule out the possibility that in this way several planets could form around these binary stars.
The discovery was made when astronomers compiled a list of the advanced twin stars in our Milky Way. They did so on the basis of existing, publicly available findings. Kluska and his colleagues counted 85 such binary star pairs. In ten pairs, the researchers found a plate with a large cavity in the infrared images.
If new observations confirm the existence of planets around evolved binary stars, and if it became apparent that the planets did not form until after one of the stars had reached the end of its life, theories of planet formation must be adapted. “Confirming or reversing this exceptional way of forming planets will be an unprecedented test for current theories,” the professor says. Hans Van WinckelDirector of the KU Leuven Institute of Astronomy.
Source: ANI