Astronomers discover an exoplanet in orbit around three suns – L’Express

One planet, three stars. Scientists have discovered an exoplanet in orbit around three suns, a strange discovery that even the two stars on the planet Tatooine in Star Wars, they wrote in their article, published Thursday in the journal Science.

If the binary star systems are relatively common, those with three stars and more are rare. On this planet, dubbed HD 131399Ab, it is possible to admire three daily sunrises and three sunsets. He also made it a day for a quarter of its orbit, which is a long period of … 140 years.

The longest day there lasts 140 years

“Imagine a world in which one could admire three dawns and three dusks daily depending on the season,” which, in this case lasts longer than human life because the orbit of the planet around the three stars hard equivalent of land 550 years, scientists write.

“For about half of the orbit, the three suns were visible in the sky, the two remaining bright least closer to each other, while their apparent separation of the main star -the most brillante- varies during the year, “said Kevin Wagner, an astronomer at the University of Arizona, a lead author of the discovery.

This proximity between the three stars is reflected, as on Earth, for a difference of night and day, says the scientist. But when the orbit of the planet is growing and the three suns move further apart, the world knows the day almost continuously for about a quarter of its orbit of 140 Earth years, researchers have determined using a mathematical model.

The planet is the most distant ever observed orbit in a multi-star system, they report.

There is 580 degrees

Located about 340 light years from Earth (one light year is equivalent to 9460 billion km) in the constellation Centauri, this planet would have formed there are only 16 million years, making it one of the youngest exoplanets discovered to date. Weighing four times that of Jupiter, HD 131399Ab is inhospitable with a temperature of 580 degrees Celsius, making it paradoxically one of the coldest for this type of giant exoplanet.

“This exoplanet is one of the few to have been directly observed and also the first with such an orbit,” said Daniel Apai, assistant professor of astronomy and planetary sciences at the University of Arizona and member of the research team. “If the planet was a little further from the main star, she would be ejected from the star system,” he explains.

“Our mathematical simulations show that this type of orbit may be stable, but only one small change can quickly become unstable,” said Professor Apai.

Discovery through Sphere

The planets in multi-star systems are of great interest to astronomers because they provide examples of planetary formations extreme scenarios, he says. According to this scientist, “these planets could potentially be as numerous as those systems with a single star (…) but they are less explored.”

The discovery of the exoplanet is the first one with Sphere (Spectro-Polarimetric High-contrast Exoplanet Research Instrument), one of the most advanced instruments in the world to hunt for exoplanets. Sensitive to infrared light, it is able to detect the thermal signature of young planets.

NASA announced the discovery in May 1284 through the exoplanets Kepler space telescope, doubling the number of those already confirmed and growing hopes of finding a sister planet Earth where life would be possible.