An international team of scientists has observed six stars similar to the sun with extraordinary dust belts.
The newly-discovered debris disks are not only bigger than the Kuiper belt but they are also extremely cold.
With a temperature of about minus 250 C they are the coldest debris disks known so far.
“We were surprised that such cold debris disks exist at all,” Alexander Krivov, the lead author of the new study, said.
By way of comparison, the Kuiper belt is about 70 C degree warmer, and some of the disks even reach room temperature.
The six debris disks are mysterious for yet another reason.
They are lacking the characteristic dust which is always released when the rocks collide.
“Small dust particles are much hotter than the temperatures observed by us,” Krivov said.
According to this, the cold debris disks only consist of bigger but at the same time not-too-big rocks. The calculations of the scientists suggest that the radius of the particles lies between several millimeters and several kilometers maximum.