(ORDO NEWS) — Protostellar disks are collections of gas and dust that orbit newborn stars. The Earth and other planets of the solar system were born from such a disk.
Satoshi Ohashi of the RIKEN Star and Planet Formation Laboratory and colleagues studied the protostellar disk in one of the star-forming regions closest to Earth.
Using data from the Atacama Large Millimeter Wave Array (ALMA) in Chile and the Very Large Array Antenna (VLA) in New Mexico, they found that the disk is 80 to 100 times wider than the distance from the Sun to the Earth.
The disk is unstable and collapses in a region about 20 astronomical units from its young star. The VLA has previously identified several clumps of matter in the same area, and their formation may be driven by this gravitational instability.
“These clusters could be precursors to gas giant planets because they are massive and dense,” says Ohashi. If this identification is correct, it would mean that the formation of planets in protostellar disks could start very early.
The researchers also measured the temperature of the dust in different parts of the disk. The disk is heated by radiation from the star, so the temperature of the dust must gradually decrease at large distances from the star.
Dust near the star can reach temperatures of -193 degrees Celsius. But on the far side of the clusters, dust temperatures are cooler.
This suggests that the clusters are blocking the star’s radiation, cooling any dust in its shadow. In the outermost parts of the disk, dust temperatures drop to around -263 degrees Celsius – just 10 degrees above absolute zero.
This shaded, cold environment could affect the chemistry of planets that form in the outer regions of the disk, Ohashi said.
The discovery could help astrophysicists understand the origin of icy planets like Uranus and Neptune that orbit the sun. “It is assumed that in the past our solar system also formed an obscured region,” says Ohashi.
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