Astronomers See a Star Crash Through the Planetary Disk of Another Star

Flash heating around the second star after it has crashed through the disc. FU Ori. Credit: Elisabeth Borchert.

What causes an otherwise unremarkable star to become over 100 times brighter? That’s a question astronomers have been pondering since 1936, when a star in Orion brightened from 16th magnitude to 8th magnitude in a single year.

The star, named FU Ori, is still bright to this day. Astronomers have come up with different explanations for the star’s brightening, but none of them provides a complete explanation.

Now we might have one.

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Both Stars in This Binary System Have Accretion Disks Around Them

Artist’s impression of one of the two stars in the FU Orionis binary system, surrounded by an accreting disk of material. What has caused this star — and others like it — to dramatically brighten? [NASA/JPL-Caltech]
Artist’s impression of one of the two stars in the FU Orionis binary system, surrounded by an accreting disk of material. Credit: NASA/JPL-Caltech

Stars exhibit all sorts of behaviors as they evolve. Small red dwarfs smolder for billions or even trillions of years. Massive stars burn hot and bright but don’t last long. And then of course there are supernovae.

Some other stars go through a period of intense flaring when young, and those young flaring stars have caught the attention of astronomers. A team of researchers are using the Atacama Large Millimeter/sub-millimeter Array (ALMA) to try to understand the youthful flaring. Their new study might have found the cause, and might have helped answer a long-standing problem in astronomy.

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