Astronomers Believe There May Be More Earth-Sized Planets Than They Thought

Some astronomers believe that exoplanet searches may be missing nearly half of all Earth-sized planets orbiting other stars. The findings by astronomers suggest that Earth-sized planets could be undiscovered in binary star systems hidden by the glare of the parent stars. Scientists note that roughly half of all stars are binary systems meaning they could be overlooking vast numbers of Earth-sized planets.

Astronomers on the project used twin telescopes from the Gemini Observatory to determine that many planet-hosting stars identified by NASA's TESS exoplanet mission are actually binary pairs with planets orbiting one of the stars in the pair. The team carefully examined the binary stars and concluded that Earth-sized planets in many binary star systems could be going unnoticed by TESS and other systems that perform transit searches.

The light from the second star in the binary pair makes it more difficult to detect changes in the light of the host star as the planet transits. The team first began by determining if some of the exoplanet host stars identified via TESS were actually unidentified binary stars. Sometimes pairs of stars that are very close together can be mistaken for single stars unless observed at extremely high resolution. The light from the second star in the binary pair makes it more difficult to detect changes in the light of the host star as the planet transits.

The team leveraged both Gemini telescopes to inspect samples of exoplanet host stars in high detail using a technique called speckle imaging. The team observed hundreds of stars that TESS had identified as potential exoplanet hosts. They discovered that 73 of those stars were binary star systems that appeared as single star systems until observed in higher resolution.

The team also studied 18 additional binary stars previously discovered among the TESS data and compared the size of detected planets in the binary systems to those in single star systems. The team found that the TESS data found large and small exoplanets orbiting single stars but only found large planets in binary systems. The scientists believe the results imply a significant number of Earth-sized planets may be in binary systems and have gone undetected.