•A new study, which shows that a planet the size of Earth could exist in stable orbits around two suns, was conducted in the 70 Ophiuchi (70 Oph AB) binary star system, located 16 light-years away. The study also found 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 planet the size of Earth 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 the speed of a star caused by the gravitational pull of another celestial body – a planet, a stellar companion, or whatever. As the star approaches Earth, its light shifts slightly to blue, then back to red as it moves away. Researchers have achieved a sensitivity of less than one meter.
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 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 candidate for an exoplanet 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 Jupiter-sized planet.
“In general, our results show that planets in S-type orbits around the primary star of 70 Oph—including 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.”
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