Artist's impression of the system as seen from the newfound planet. HD 131399 A is at the center. The other two stars can be seen in the distance / Photo: ESO/L. Calçada/M. Kornmesser

HD 131399Ab – In this strange newfound alien world, there is no night.

Using ESO’s Very Large Telescope (VLT), astronomers have found a young Jupiter-like planet in a system with triple-star system.

The newfound alien world, named HD 131399Ab, resides in the HD 131399 system, about 320 light-years from Earth in the constellation of Centaurus.

HD 131399Ab located very far from its biggest star, named HD131399A. Because it is so far away, it can be said that it is located on the border of the orbit of HD131399A.

On the other hand, HD131399Ab is located very close to the other two stars, HD131399B and HD131399C.

The planet is about 16 million years old, its atmosphere was shown to contain both water and methane through the use of near-infrared spectroscopy.

Scientists believe it is unlikely that the planet harbors life due to it being gaseous. The planet is said to have “no liquid water, extremely powerful winds, and no surface; just below the uppermost layer of the atmosphere it rains liquid iron droplets.”

With four times the size of Jupiter and its position, the new planet should have been knocked out of its orbit, however it did not happen. Astronomers suspect, it is because not only HD131399Ab orbiting the star but also orbiting each other.

Although repeated observations will be needed to precisely determine the trajectory of HD 131399Ab, VLT observations and simulations seem to suggest the following scenario:

  • HD 131399A is orbited by the less massive stars, HD 131399B and HD 131399C, at about 300 astronomical units (AU);
  • HD 131399B and HD 131399C twirl around each other like a spinning dumbbell, separated by a distance roughly equal to that between the Sun and Saturn (10 AU);
  • the planet HD 131399Ab travels around the host star HD 131399A 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 HD 131399A and the HD 131399B/C star pair.

It is really a complex system in the Centaurus constelation, one of the largest constelation in the sky.

“It is much more extreme than what is known by the experts in the dynamics of the planets,” said Kevin Wagner from the university of Arizona who discovered the planet as quoted “Popular Science” on Friday (July 8).

The weirdness of the system triggers other peculiarities in HD 131399Ab planet, during about a quarter of the orbit or four months on the planet ~ the equivalent of 100 – 140 years on earth ~ from this planet can be seen the three stars at once, which means the view of the sunrise and sunset at a time.

When a larger star is rising, two of the smaller stars are setting: there will be days without nights. If there are humans living on the planet in this period, throughout their lives they will never see the nights.

“This is the system where I do not want to create a calendar”, said Daniel Apai an assistant professor of astronomy and planetary sciences at the University of Arizona, who leads a research group dedicated to finding and observing exoplanets.

The discovery of this planet was published in the Journal Science on Thursday (July 7). The discovery of the planet is special because it’s done with direct imaging. Most planets discovered by the transit method, watching the flicker of starlight when a planet passes by.

The discovery by direct imaging was made possible due to the large size of HD 131399Ab. However, among the planets discovered by direct imaging methods, the size of the HD 131399Ab classified as the smallest one.