A few weeks ago, people were sharing news about a planet that, like Tatooine on Star Wars, orbited two stars. This was pretty cool, but as usual, it didn't take long for something to one-up even this.
Scientists at the University of Arizona have discovered a planet that circles THREE stars, in the constellation of Centaurus, called HD 131399Ab. What makes this planet so surprising is that according to scientist's predictions, the orbit of a planet in a three star system would be so unstable that it would be ejected pretty quickly. The configuration of this planet's orbit, however, is such that its path follows just the right course to keep it balanced among its three host stars, in a fairly stable orbit.
Not only is this planet's discovery special because of the the number of stars this planet orbits, but it also because this is one of the few exoplanets discovered through direct observation. Most exoplanets are found because of variations in the light of the stars they orbit, or other indirect methods. HD 131399Ab was actually detected by its own heat signature by the SPHERE instrument on ESO's Very Large Telescope in Chile.
Other things that make this planet unique and cool:
- HD 131399Ab has the widest orbit known of a planet within a multi-star system.
- At 16 million years old, it is also one of the youngest exoplanets we've discovered to date.
- Its temperature of 580 degrees Celsius makes it one of the coolest exoplanets discovered with direct imaging (a cold planet is harder to find via infrared than a warm planet).
- It is only 4 times the mass of Jupiter (only?), so it is also one of the least massive exoplanets we've discovered via direct observation.
HD 131399Ab is the first planet discovered by the SPHERE instrument, which is an infrared sensitive devise that can pick up heat signatures of young planets while correcting for atmospheric disturbances and blocking out the blinding light of the planets' host stars that would normally make observing them difficult. This will help scientists learn more about exoplanets than ever before.
Meanwhile, HD131399 Ab has given scientists a lot to celebrate--and to look forward to.
"It is not clear how this planet ended up on its wide orbit in this extreme system, and we can't say yet what this means for our broader understanding of the types of planetary systems," says Kevin Wagner, a PhD student at the University of Arizona. "But it shows that there is more variety out there than many would have deemed possible."
Any questions? Is there anything you'd like to see covered in a future science article? Ask away in the comments!
Melanie R. Meadors is the author of fantasy and science fiction stories where heroes don’t always carry swords and knights in shining armor often lose to nerds who study their weaknesses. She’s been known to befriend wandering garden gnomes, do battle with metal-eating squirrels, and has been called a superhero on more than one occasion. Her work has been published in several magazines, and she was a finalist in the 2014 Jim Baen Memorial Science Fiction Contest. Melanie is also a freelance author publicist and publicity/marketing coordinator for both Ragnarok Publications and Mechanical Muse, an independent gaming company. She blogs regularly for GeekMom and The Once and Future Podcast. Her short story “A Whole-Hearted Halfling” is in the anthology Champions of Aetaltis, available now on Amazon. Follow Melanie on Facebook and on Twitter as @MelanieRMeadors.