Astronomers have discovered the KOI-5Ab planet in the constellation Cygnus. It is located in a system of three stars similar to the Sun. Now scientists want to find out how the planets in multi-star systems differ from those that revolve around a single star.

KOI-5Ab was first discovered decades ago using the Kepler space telescope. Back then, scientists noticed that the object had two stars: KOI-5B and KOI-5C. Therefore, they had doubts about whether there really was a planet there. Scientists decided that this object is too complicated, and it is better to work on confirming other exoplanets.

Astronomers have now confirmed the existence of 4,331 exoplanets, but most of them exist in one-star systems. Only less than 10% of confirmed exoplanets are multi-star systems. NASA says this may happen because it is harder to detect planets in multi-star systems.

In 2018, Kepler was replaced by the TESS telescope, and scientists decided to continue the research of the KOI-5 system. The telescope also sent a signal about a possible exoplanet. The researchers found that an exoplanet is orbiting around the KOI-5A star.

KOI-5 triple star system
KOI-5 triple star system

Scientists also found that the exoplanet is probably a gas giant, whose mass is seven times the mass of the Earth and is half the mass of Saturn (one of the largest planets in the solar system).

KOI-5Ab makes a complete revolution around the KOI-5A sun in 5 days. The stars KOI-5A and KOI-5B orbit each other in 30 years, and the third star, KOI-5C, is located farther from the other two, so it makes a complete revolution in 400 years.

According to astronomers, the exoplanet's orbit is distorted, but it is not known exactly why. They suggest that the second star (KOI-5B) gravitationally pushed the planet during its inception, which distorted the orbit.

Astronomers still have many questions about how and when planets can form in multi-star systems, as well as what features such planets have. To answer these questions, they will continue to research KOI-5Ab.