Rapid Disappearance Of Pre-Planetary Dust Disk Challenges Theories


Researchers have observed a very fast drop in infrared emissions from the Sun-like star TYC 8241 2652. This rapid drop may be an indication that the circumstellar disk of dusty debris, from which planets form, has experienced a very drastic (and, as of now, unknown) event.

In observations made in 2009 by researchers from the the University of California San Diego, a dense disk made of dust was observed surrounding the distant sun. TYC 8241 2652 is located about 456 light years away.

But recent observations made by ground telescopes and satellites show that the dust disk cloud has nearly disappeared in only the last two years, greatly challenging current theories.

“The star seems to have gone from hosting substantial quantities of dusty ejecta, in a region analogous to where the rocky planets orbit in the Solar System, to retaining at most a meagre amount of cooler dust.”

The research was done by observing the levels of infrared radiated from the distant star. And during only two years, the infrared heat emissions appear to have dropped by a factor of 30, this suggests that a very dramatic change in the dust disk surrounding the star may have occurred.



Previous research has suggested that young suns commonly are surrounded by dust disks, and that it’s from these disks that all planetary bodies form.

Though, since the process would likely take millions of years to make a planet, it has never been observed. This recent, observed disappearance of the dust disk, is suggesting that, at the very least, some of the steps in planet formation may occur very rapidly.

Margaret Moerchen, a researcher at the Leiden Observatory, says: “perhaps the most exciting possibility is that the brightness drop represents a stage of terrestrial-planet formation that occurs so quickly that we have not been lucky enough to glimpse it until now.”

She continues: “gravitationally bound dust grains experience successive cratering or wholly destructive collisions that eventually yield grains small enough to be blown out of the system.”

The researchers think that the rapid drop may be explained as the effect of the collision of large young planets, resulting in dust being blown out of the system. This could explain the very fast drop in observed infrared heat signatures. If so, this is a phase of early planet formation that we have not until now observed.

If that is what has happened, then, according to the researchers, in the next couple of decades a new dust disk will form around the star. If this is observed than it will lend a lot of credibility to the theory.

“This system has clearly undergone a drastic event that promises to provide unique insight into the process by which rocky planets form.”

Source: Nature
Image Credits: Gemini Observatory/AURA artwork by Lynette Cook

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