ESO: A Surprising Planet with Three Suns

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bystander
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ESO: A Surprising Planet with Three Suns

Post by bystander » Thu Jul 07, 2016 8:05 pm

A Surprising Planet with Three Suns
ESO Science Release | VLT | SPHERE | 2016 July 07
[c][imghover=https://cdn.eso.org/images/screen/eso1624g.jpg]https://cdn.eso.org/images/screen/eso1624d.jpg[/imghover]SPHERE observations of the planet HD 131399Ab - Credit: ESO/K. Wagner et al[/c][hr][/hr]
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A team of astronomers have used the SPHERE instrument on ESO’s Very Large Telescope (VLT) to image the first planet ever found in a wide orbit inside a triple-star system. The orbit of such a planet had been expected to be unstable, probably resulting in the planet being quickly ejected from the system. But somehow this one survives. This unexpected observation suggests that such systems may actually be more common than previously thought. ...

Luke Skywalker's home planet, Tatooine, in the Star Wars saga, was a strange world with two suns in the sky, but astronomers have now found a planet in an even more exotic system, where an observer would either experience constant daylight or enjoy triple sunrises and sunsets each day, depending on the seasons, which last longer than human lifetimes.

This world has been discovered by a team of astronomers led by the University of Arizona, USA, using direct imaging at ESO’s Very Large Telescope (VLT) in Chile. The planet, HD 131399Ab, is unlike any other known world — its orbit around the brightest of the three stars is by far the widest known within a multi-star system. Such orbits are often unstable, because of the complex and changing gravitational attraction from the other two stars in the system, and planets in stable orbits were thought to be very unlikely.

Located about 320 light-years from Earth in the constellation of Centaurus (The Centaur), HD 131399Ab is about 16 million years old, making it also one of the youngest exoplanets discovered to date, and one of very few directly imaged planets. With a temperature of around 580 degrees Celsius and an estimated mass of four Jupiter masses, it is also one of the coldest and least massive directly-imaged exoplanets. ...

Although repeated and long-term observations will be needed to precisely determine the planet's trajectory among its host stars, observations and simulations seem to suggest the following scenario: the brightest star is estimated to be eighty percent more massive than the Sun and dubbed HD 131399A, which itself is orbited by the less massive stars, B and C, at about 300 au (one au, or astronomical unit, equals the average distance between the Earth and the Sun). All the while, B and C twirl around each other like a spinning dumbbell, separated by a distance roughly equal to that between the Sun and Saturn (10 au).

In this scenario, planet HD 131399Ab travels around the star A in an orbit with a radius of about 80 au, about twice as large as Pluto’s in the Solar System, and brings the planet to about one third of the separation between star A and the B/C star pair. The authors point out that a range of orbital scenarios is possible, and the verdict on the long-term stability of the system will have to wait for planned follow-up observations that will better constrain the planet’s orbit. ...

Newly-Discovered Planet Has 3 Suns
NASA GSFC | Univ of Arizona | 2016 July 07

Direct Imaging Discovery of a Jovian Exoplanet within a Triple-star System - Kevin Wagner et al
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Re: ESO: A Surprising Planet with Three Suns

Post by neufer » Thu Jul 07, 2016 8:21 pm

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Scientists discover strange planet with three suns

Post by Ann » Fri Jul 08, 2016 7:57 am

HD 131399Ab: Scientists discover strange planet with three suns
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An international team of astronomers have announced the discovery of a strange planet in a faraway solar system that contains not just one sun, but three...

The cosmic body is believed to be relatively young, about 16 million years old, which makes it one of the youngest planets discovered outside our solar system to date...

It orbits the brightest of the three stars on a very long and wide path.

"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," first author Kevin Wagner, a first-year PhD student who discovered HD 131399Ab, said.

"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," Mr Wagner added.

"As the planet orbits and the stars grow further apart each day, they reach a point where the setting of one coincides with the rising of the other."

The result is "near-constant daytime for about one-quarter of its orbit, or roughly 140 Earth-years"...
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Re: Scientists discover strange planet with three suns

Post by neufer » Fri Jul 08, 2016 11:38 am

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