Astronomers generally agree that planets form out of the massive disks of leftover debris that surround most newborn stars. As these disks of gas and dust orbit their stars, small clumps of material coalesce, ultimately growing larger and larger until they eventually reach planetary status. However, not all planets make it that far. Sometimes, two nascent planets catastrophically collide — and stars apparently do not mourn their dead.In a study published July 18 in The Astronomical Journal, a team of researchers announced they may have, for the first time ever, witnessed a star feeding on the leftover remains of one such planetary collision. These novel observations not only show that a star can devour its own planets, but also bring astronomers one step closer to fully understanding how planets form — or in this case, are destroyed.“Computer simulations have long predicted that planets can fall into a young star, but we have never before observed that,” said lead author Hans Moritz Günther, a researcher at MIT’s Kavli Institute for Astrophysics and Space Research, in a press release . “If our interpretation of the data is correct, this would be the first time that we directly observe a young star devouring a planet or planets.”To carry out the study, the researchers used NASA’s Chandra X-ray Observatory to observe the peculiar star RW Aur A — the largest of a pair of young, low-mass stars in the RW Aur system. The star, which is only 10 million years old and located some 450 light-years from Earth, has drawn astronomers attention since 1937, thanks in large part to the mysterious dimming episodes it experiences.Every few decades for over 80 years, astronomers watched as the star would fade for about a month before brightening back up again. However, in 2011, astronomers noticed the star dimmed for about six months before returning to its baseline brightness. Then, just three short years later, they witnessed it darken again. And this time, the dimming lasted for over two years. Because RW Aur A is dimming more often and for longer periods of time, it begs the question: What is passing in front of the star and obscuring its light?To answer this, the researchers recorded X-ray emissions from the star beginning in January 2017, as RW Aur A started another dimming event. “We want to study the material that covers the star up, which is presumably related to the disk in some way,” said Günther. “It’s a rare opportunity.”As the X-rays passed through the disk of gas and dust that surrounds the young star, they picked up the fingerprints of the material within the disk. “The X-rays come from the star, and the spectrum of the X-rays changes as the rays move through the gas in the disk,” said Günther. “We’re looking for certain signatures in the X-rays that the gas leaves in the X-ray spectrum.”By analyzing how the X-ray light was filtered through the star’s debris disk, the team concluded three things: The star has a lot of material surrounding it; the star is significantly hotter than expected; and, surprisingly, the star’s outer layer is loaded with iron — much more than was seen before or is found in otherwise similar stars.“Here, we see a lot more iron, at least a factor of 10 times more than before, which is very unusual, because typically stars that are active and hot have less iron than others, whereas this one has more,” said Günther. “Where does all this iron come from?”