新研究: 16光年先の二つの太陽を持つ、地球サイズの惑星が存在する可能性

著者 / 編集者: Cem Yıldız•12 October 2026

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A new study, which shows that a planet orbiting around two suns could exist in the habitable zone on stable orbits on a world-sized scale, was conducted in the 70 Ophiuchi (70 Oph AB) binary star system, located 16 light-years away. The study also revealed that no Jupiter-mass giant planets exist in this system. Stephen Kane, an astrophysicist at the University of California, Riverside (UCR), said, “You might think that the second star would come in like a wrecking ball and make it impossible for a world-sized planet to exist in the habitable zone. But these simulations show that this is not necessarily the case.”

The second successful method for finding planets, the RV method, is responsible for the discovery of more than 1,200 exoplanets. This method measures tiny changes in a star’s speed caused by the gravitational pull of another celestial body—whether it’s a planet, a stellar companion, or something else. As the star approaches Earth, it shifts its light slightly toward blue, then back toward red as it moves away. Researchers have achieved a sensitivity of less than a meter for this measurement.

The researchers also ruled out the presence of giant exoplanets larger than Jupiter, which is the distance of five astronomical units (AU) from the primary star—about the distance of a gas giant the size of Jupiter in our own solar system. This is interesting because in 1855, British astronomer William Jacob claimed to have discovered a planet in 70 Oph AB, making it the first exoplanet candidate host; University of Michigan (U-M) researchers note. Jacob’s claim did not stand up to scrutiny, but later measurements showed a “wobble” that could be explained by a planet the size of Jupiter.

“In general, our results show that planets in S-type orbits around the primary star of 70 Oph—including those in the habitable zone—could sustain rocky planets. If star binary systems can host solar-like planets, 70 Oph is one of the best places to look.”

The research was published in a journal.