Illustration of K2-33b (NASA/JPL-Caltech)
This week Texas astronomers announced their discovery of a giant new exoplanet, which orbits close to its star. It’s a young planet: only 11 million years old. And it’s a large planet: 5 times the size of the Earth. What’s unusual is that it’s very close to its star, with an orbit of less than 6 days.
Andrew Mann and his team of 17 astronomers made use of data from the Kepler spacecraft and the IGRINS spectrometer at the McDonald Observatory in West Texas. According to Mann, the planet – named K2 33 B – is “actually, pretty close. It’s about 150 parsecs, which is a little over 300 light years away.”
Mann’s team and a competing group from Caltech were looking for the same thing: young planets around young stars. “It took a long time to observe. And actually when we found it – at the point we found the signal – we weren’t sure it was real.”
But they didn’t have a long to observe. In a manner of speaking, the sun photo-bombed the picture.
“The star was behind the sun,” said Mann. “The Earth was not in a good position to observe it, too confirm our findings. And so we were only were able to prove it, you know, sort of quickly as it rose again (in) January (and) February. It took a little while. But we were able to get enough follow-up measurements to prove to us that it was real.”
A mystery to the astronomers was how does a planet this young, orbit so close to its star. One theory is through disc migration.
“Planets form in this disc of gas and dust,” explains Mann. “It’s like the planets moving through a fluid, so it slows it down. And that causes it to migrate inwards. So this one almost certainly acted through disc migration, because of the fact that it got there so young.”