TOI-849b is so close to its star that a “year” lasts 18 hours. Bless.
University of Warwick / Mark Garlick
If we can agree on one thing about 2020, it would be the following: it would be perfect if it only took 18 hours. This dream year is real on TOI-849b, an exoplanet that is approximately 730 light years away from Earth. The planet is so close to its star that it only takes 18 hours to reach full orbit.
But as you can imagine, TOI-849b is especially hot because it’s so close to the sun. Like 2,700 degrees Fahrenheit hot.
And it’s incredibly strange: the team of astronomers who discovered it somehow find it naked. Its size suggests that it should be a giant gas planet – think of Jupiter – but it isn’t. Instead, the rocky core of the planet orbits the star.
The study, published in the journal Nature on Wednesday, describes the discovery of TOI-849b orbiting the sun-like star TOI-849. It was discovered by researchers The NASA TESS telescope, a space-based observatory looking for a periodic darkening of a star – a potential sign that it is accompanied by a planet. The La Silla Observatory of the European Southern Observatory helped characterize the unusual world.
TOI-849b is about 40 times as massive as the Earth and 3.5 times as wide. It exists in the “hot Neptune desert” region around its star – a place where astronomers don’t normally find these types of planets because they are crushed by the neighboring massive furnace.
But then there’s TOI-849b hanging in the scorching heat. According to the modeling used by the team, the density of the planet suggests that it should have been able to accumulate a lot of hydrogen and helium gas, but it seems to have only a fraction of what is expected.
“Such a small amount of hydrogen and helium is really amazing for such a massive planet,” said Christoph Mordasini, physicist at the University of Bern and co-author of the study, in a press release. “We would expect such a massive planet to have accumulated large amounts of hydrogen and helium when it was created.”
The researchers believe they have discovered an “exposed planetary nucleus”, and if their theory is correct, it would be the first time that such a discovery has been made. But how did it happen?
Mordasini notes that TOI-849b may have lost its gas during its formation because the nearby star stripped it to the core due to its enormous attraction. A collision with another planet may also have contributed to this.
It may also have forgotten to get dressed. If the planet had formed in a region of space where there was no dust, gas, or dirt to gobble up, it might never have been able to enrich the material that would normally be expected from a planet of this size.
“Our discovery proves that such planets exist and we can track them down,” said David Armstrong, astrophysicist at the University of Warwick. “We have the opportunity to look at the nucleus of a planet in a way that we cannot in our own solar system.”
Look at that:
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