NASA has discovered a three-star exoplanet, one with a bizarre orbit that has left astronomers baffled.
The planet, known as KOI-5Ab, was discovered in 2009 by NASA’s Kepler Space Telescope, but was “abandoned” by scientists because the space telescope had easier candidates to identify.
“KOI-5Ab was abandoned because it was complicated and we had thousands of candidates,” David Ciardi, chief scientist at NASA’s Exoplanet Science Institute, said in a statement. “It was easier to pick than KOI-5Ab and we learned something new from Kepler every day, so that KOI-5 was largely forgotten.”
KOI-5Ab is about 1,800 light-years from Earth. A light year, which measures distance in space, is about 6 trillion miles.
However, thanks to NASA’s Transiting Exoplanet Survey Satellite (TESS) and other Earth-based telescopes, KOA-5Ab has been given new life, with researchers discovering its confusing orbit.
Because of its size, KOA-5Ab is likely a gas giant, similar to Jupiter or Saturn, but it orbits a star in its star system, KOA-5A, once every five days. It is also unaligned from at least one of the other two stars and possibly both.
“We don’t know many planets that exist in triple star systems and this one is extra special because its orbit is skewed,” added Ciardi. “We still have many questions about how and when planets can form in multi-star systems and how their properties relate to planets in single-star systems. By studying this system in more detail, we may be able to gain insight into how the universe makes planets. “
In contrast, KOI-5A revolves around KOI-5B once every 30 years. KOI-5C orbits every two every 400 years, causing the four celestial bodies to skew due to different planes.
It is unclear what caused the skewed orbit, although they “believe the second star kicked the planet by gravity during its development, skewed its orbit and made it migrate inward,” added the NASA statement. Triple galaxies are believed to make up about 10 percent of all galaxies.
The findings were recently presented at a virtual meeting of the American Astronomical Society.
Researchers have discovered other three-star planets in recent history. In July 2019, exoplanet LTT 1445Ab was found orbiting one of three suns, all of which are described as middle to late-aged red dwarfs.
In September 2020, researchers discovered that the GW Orionis galaxy, located on the edge of the constellation Orion, has two stars orbiting each other, with the third orbiting the two siblings at a distance of about 740 million miles. Inside the rings could be dust, or the start of a young exoplanet, which could explain the misalignment of the system’s gravity.
In all, more than 4,000 exoplanets have been discovered by NASA, of which about 50 were believed to be potentially habitable as of September 2018. They have the correct size and orbit of their stars to support surface water and, at least theoretically, to support life.