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More Aries

December 27, 2017

Things are heating up for a planet that orbits the brightest star in Aries, the ram. The star is expanding to become a giant, so it’s pumping more energy into space. That will make temperatures extremely uncomfortable on the planet.

The star is Hamal. It’s high in the south in early evening, almost directly above the Moon.

Hamal is at the end of its life. It’s converted the original hydrogen fuel in its core to helium. Now, it’s getting ready to fuse the helium to make other elements. That’s making the core hotter, which, in turn, has caused the star’s outer layers to puff up — to more than a dozen times the diameter of the Sun. And that’s made Hamal about 90 times brighter than the Sun.

Hamal has only one known planet — a giant that’s heavier than Jupiter, the biggest planet in our own solar system. On average, it’s only about as far from Hamal as Earth is from the Sun — much closer in than Jupiter is. So any given area of the planet’s surface receives hundreds of times more energy than Jupiter does.

If the planet is a ball of gas like Jupiter, then the extra heat is causing its atmosphere to puff up — and causing a lot of it to stream away into space.

And over the next few million years, the planet will get even hotter, because Hamal will get even bigger. The extra energy may eventually erode the planet’s entire atmosphere. Or the planet may spiral into the star. Either way, things are going to get a lot hotter for Hamal’s only known planet.


Script by Damond Benningfield

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