![]() The simplest explanation is that the misaligned disks are likely caused by the gravitational pull of two planets in slightly different orbital planes. It makes the system much more complex than we originally thought," he said. "We've never really seen this before on a protoplanetary disk. Over time they've now separated and split into two shadows. They were so close to each other in the earlier observation they were missed. The best solution the team came up with is that there are two misaligned disks casting shadows. I was flummoxed at first, and all my collaborators were like: what is going on? We really had to scratch our heads and it took us a while to actually figure out an explanation." "When I first looked at the data, I thought something had gone wrong with the observation because it wasn't what I was expecting. "We found out that the shadow had done something completely different," said Debes, who is principal investigator and lead author of the study published in The Astrophysical Journal. John Debes of AURA/STScI for the European Space Agency at the Space Telescope Science Institute in Baltimore, Maryland, compared the TW Hydrae disk to Hubble observations made several years ago. The second shadow was discovered in observations obtained on June 6, 2021, as part of a multi-year program designed to track the shadows in circumstellar disks. Because the TW Hydrae system is tilted nearly face-on to our view from Earth, it is an optimum target for getting a bull's-eye-view of a planetary construction yard. In its infancy, our solar system may have resembled the TW Hydrae system, some 4.6 billion years ago. TW Hydrae is less than 10 million years old and resides about 200 light-years away. The two disks are likely evidence of a pair of planets under construction. This could be from yet another disk nestled inside the system. Now, a second shadow – playing a game of peek-a-boo – has emerged in just a few years between observations stored in Hubble's MAST archive. One explanation is that an unseen planet's gravity is pulling dust and gas into the planet's inclined orbit. The shadow isn't from a planet, but from an inner disk slightly inclined relative to the much larger outer disk – causing it to cast a shadow. In 2017, astronomers reported discovering a shadow sweeping across the face of a vast pancake-shaped gas-and-dust disk surrounding the red dwarf star. The young star TW Hydrae is playing "shadow puppets" with scientists observing it with NASA's Hubble Space Telescope. TW Hydrae gives astronomers a ringside seat to how our solar system may have looked during its formative years. This is not a surprise because the planets in our solar system have orbital planes that vary in tilt by a few degrees from each other. Each planet is gravitationally pulling on material near the star and warping what would have been a perfectly flat, pancake-shaped disk if no planets were present. The disks are proxies for unseen planets around the star. So, the system looks increasingly complicated with at least three nested disks slightly tilted relative to each other. Astronomers used Hubble to find a second shadow emerging from yet another inner disk, that is tilted to the two outer disks. ![]() The shadow can only be clearly seen because the system is tilted face-on to Earth, giving astronomers a bird's-eye view of the disk as the shadow sweeps around the disk like a hand moving around a clock.īut a clock has two hands (hours and minutes) sweeping around at different rates. The shadow is cast by an inner disk of dust and gas that is slightly tilted to the plane of the outer disk. In 2017, astronomers were surprised to see a huge shadow sweeping across a disk of dust and gas encircling the nearby young star TW Hydrae. Our universe is so capricious it sometimes likes to play a game of hide and seek. ![]() Four Successful Women Behind the Hubble Space Telescope's Achievements.Characterizing Planets Around Other Stars.Measuring the Universe's Expansion Rate.
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