The Newly Discovered Star CI Tau Challenges Our Current Models for Star Systems

Tuesday, 16 October 2018 - 1:08PM
Astronomy
Space
Tuesday, 16 October 2018 - 1:08PM
The Newly Discovered Star CI Tau Challenges Our Current Models for Star Systems
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Composite adapted from Pixabay & NASA/JPL-Caltech.
It must be hard to be an astronomer or astrophysicist—every week, a new discovery (like Swift J0243.6+6124) seems to challenge their models and throw a wrench into our ongoing quest to understand what the heck is going on in this universe. Now there's been another big, weird discovery: a young star named CI Tau surrounded by massive gas giants, despite all our models claiming that such a star system should be impossible.

CI Tau is only 2 million years old but is already host to four planets, including CI Tau b (which is about 11 times the mass of Jupiter), a Jupiter-sized planet, and two Saturn-sized planets. One of the strange things about this system is that CI Tau b apparently formed extremely close to the star, which should be impossible due to the effects of CI Tau's gravity and radiation. If the gas giant didn't form there, then it must have formed farther out in the system, then migrated closer...but that process is estimated to take hundreds of millions of years.

The orbits of CI Tau's planets are just as weird. In fact, it has the most extreme distribution of planets ever observed: the outermost planet, one of the Saturn-like bodies, orbits at a distance that's roughly 1,000 times that of CI Tau b. For comparison, Pluto orbits the Sun at a distance 102 times that of Mercury.

According to Cambridge University's Cathie Clark: "Planet formation models tend to focus on being able to make the types of planets that have been observed already, so new discoveries don't necessarily fit the models. Saturn mass planets are supposed to form by first accumulating a solid core and then pulling in a layer of gas on top, but these processes are supposed to be very slow at large distances from the star. Most models will struggle to make planets of this mass at this distance."

Astronomers are going to be keeping an eye out for other star systems like CI Tau, but until then the story behind its bizarre composition will remain an intriguing puzzle for scientists.

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