The Star Tau Boo Flips Its Magnetic Field, Too

Scientists watched the magnetic field of a star 51 light years away flip back and forth

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The Sun does a lot of crazy things: it spawns roiling loops of superheated plasma that stretch for thousands of milesit blows huge chunks of itself off into space and, every 11 years or so, its insides do a little flip. The solar magnetic field turns on its head, and the north pole becomes the south, and the south, the north. The sun is actually gearing up for one of these flips, says NASA, and it should take place any time now.

It’s nice to see, every now and again, some of these behaviors elsewhere in the universe—to know that the sun might be strange, but not too strange. For the first time, says the American Museum of Natural History, scientists reported seeing another star go through a similar magnetic field flip.

As described in a new study, scientists have been watching as a star, known as Tau Boötis (and nicknamed Tau Boo), flipped its magnetic field back and forth. The behavior isn’t exactly the same as the Sun’s, though. Where the Sun takes 22 years to go through a full cycle, flipping and flipping back, Tau Boötis does it in just two.

It’s still mostly a bunch of conjecture, but the scientists in their study have already suggested a way that they think Tau Boötis’ flip is different than the Sun’s, other than the rapid clip. Tau Boötis has a huge planet orbiting right up close. The scientists think that this huge planet, much like Jupiter but with an orbit that takes just 3.3 days, may be affecting the star’s magnetic field. Astronomy explains:

“For Tau Boo, tidal interactions between the star and the planet might be an important factor in accelerating the cycle, but we can’t be sure of the cause,” said Fares.

Tau Boo spins on its axis once every 3.3 days — the same amount of time as it takes the hot Jupiter to complete one orbit. One hypothesis for Tau Boo’s rapid cycle is that the planet makes it rotate faster than usual, and this is affecting the generation of the magnetic field.

“There are still some big questions about what’s causing Tau Boo’s rapid magnetic cycle,” said Fares. “From our survey, we can say that each planetary system is particular, that interactions affect stars and planets differently, and that they depend on the masses, distance, and other properties.”

We still don’t really know why the Sun’s magnetic field flips like this in the first place. So, having a second example of stellar magnetic field flipping to compare the sun’s behavior against should be extremely helpful to scientists working to understand this phenomenon.

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