Exoplanet with three suns and a stable orbit surprises astronomers

Exoplanet with three suns and a stable orbit surprises astronomers

A team of astronomers led by the University of Arizona, USA, have discovered an exoplanet, named HD 131399Ab, which has three stars. As a result, it likely experiences triple sunrises and sunsets each day, and constant light or darkness for certain periods of time. The planet’s orbit is one of the widest known within a multi-star system, lasting 550 Earth-years. According to the astronomers, for half of the planet’s orbit, three stars are visible in the sky. The planet revolves around star A, which is the biggest and the brightest of the three and is estimated to be 80% bigger than the Sun. Stars B and C orbit around star A, but they also twirl around each other, and are distanced by about 10 au (1 astronomical unit = the average distance between Earth and the Sun). On the other hand, the planet’s orbit around star A has a radius of about 80 au. This extreme multi-star system has made the astronomers wonder about the stability of the planet’s position in the system as three stars exert gravitational influence on it. While multi-star systems are as common as single-star systems such as our own, astronomers are intrigued by HD 131399Ab and its positioning, and have stated that any tumult in the system can result in the planet exiting from the system.

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