Massive Planet Found with Three Suns has Triple Sunsets and Sunrises

If you thought Luke Skywalker's home planet, Tatooine, was a strange world with its two suns in the sky, imagine this: a planet with either constant daylight or triple sunrises and sunsets each day depending on the seasons (which last longer than human lifetimes). Such a world has been discovered by a team of astronomers led by the University of Arizona using direct imaging. The planet, HD 131399Ab, is unlike any other known world – one with, by far, the widest known orbit within a multi-star system. Located about 340 light years from Earth in the constellation Centaurus, HD 131399Ab is believed to be about 16 million years old, making it one of the youngest exoplanets discovered to date. With a temperature of 850 kelvins (about 1,070 F or 580 C) and weighing in at an estimated four Jupiter masses, it is also one of the coldest and least massive directly-imaged exoplanets. For about half of the planet’s orbit, which lasts 550 Earth-years, three stars are visible in the sky, the fainter two always much closer together, and changing in apparent separation from the brightest star throughout the year. For much of the planet’s year the stars appear close together, giving it a familiar night-side and day-side with a unique triple-sunset and sunrise each day. As the planet orbits and the stars grow farther apart each day, they reach a point where the setting of one coincides with the rising of the other – at which point the planet is in near-constant daytime for about one-quarter of its orbit, or roughly 140 Earth-years. Planets in multi-star systems are of special interest to astronomers and planetary scientists because they provide an example of how planet formation functions in these extreme scenarios. While multi-star systems seem exotic to us in our orbit around our solitary star – multi-star systems are in fact just as common as single stars.



https://youtu.be/3zfs-rJAKho