(ORDO NEWS) — Astronomers at the University of Warwick have discovered a new phenomenon called the “rolling shadow” effect, which describes the orientation of disks in forming planetary systems and their movement around a host star. This effect also provides clues as to how they might evolve over time.
Stars are born when a large cloud of gas and dust collapses on itself. The remaining material that doesn’t hit the star ends up swirling around it, much like water swirling around a drain. This swirling mass of gas and dust is called the protoplanetary disk, and it is in this disk that planets like Earth are born.
Protoplanetary disks are often thought to be shaped like dinner plates thin, round, and flat. However, recent images taken by the ALMA telescope show that this is not always the case.
Some of the disks observed by ALMA have shadows where the part of the disk closest to the star blocks out some of the starlight and casts a shadow on the outer part of the disk.
From this shadow pattern, we can conclude that the inner part of the disk is oriented quite differently than the outer one, which is called a broken disk.
In this study, the team used high-end computers to model a broken disc in 3D. The team then simulated the observation, simulating what such a disk would look like if viewed through a telescope and how it would change over time.
As the inner disk moved under the gravitational pull of the central star, the shadow it cast moved across the outer disk. But instead of the shadow moving across the disk like an hour hand, as expected, it wobbled back and forth like a saw.
Thus, although the inner disk kept spinning in the same direction, its shadow looked like it was rocking back and forth. The team suggests that this is caused by a geometric projection effect, which is likely to occur in all broken discs.
Dr. Rebecca Nealon says: “The James Webb Telescope promises to give us a glimpse of embryonic planetary systems in unprecedented detail, and with our new models we will be able to learn much more about the birth of planets.”
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