Within our solar system, the Earth is unique. Only a few celestial objects have an atmosphere, and it’s the only one capable of supporting life… as far as we know. How many Earths are there? New research suggests that it may be more than we thought. Now NASA astronomers say we might be missing out on many exoplanets like Earth in binary solar systems. That could increase the chances of finding habitable worlds in the universe.
We live on a planet that orbits a single star, but multiple-star systems are standard. At least one-third of the solar systems in the Milky Way contain two or more stars. Depending on who you ask, it may be closer to half. Astronomers can see these stars as a single point of light if they are close together and far enough apart. This can pose a problem for planet-hunters.
There are more than 4,000 confirmed exoplanets, the majority of which are considerable. It’s a consequence of how we detect them.
Researchers rely on features such as gravity and light variation to identify exoplanets because it is difficult to image these worlds directly. NASA’s Transiting Exoplanet Survey Satellite (TESS) uses the transit method as the most effective. Planets transiting in front of their host star can be observed by watching for dips in light. Kepler also discovered thousands of exoplanets this way.
NASA’s Ames Research Center used the Gemini North and South telescopes in Chile and Hawaii to observe nearby TESS targets. There were 73 binary pairs among those stars. Additionally, they observed 18 other binary systems scanned by TESS using the WIYN 3.5-meter telescope. Studying the populations of exoplanets in these solar systems, the researchers found a surprising result: TESS detected both small and large Earth-like exoplanets orbiting single stars, but it only detected large gas giant planets orbiting binary stars.
This research implies that Earth-like exoplanets could be hiding in binary systems, and our methods of detection aren’t good enough to see them. According to study leader Katie Lester, minor planets are liable to get lost in the brightness of a binary system, making it difficult to track their transits accurately.
This work complicates astronomy. As long as we rely on the transit method to catalog exoplanets, researchers must pay particular attention to whether or not a system is binary. We could be getting an incomplete picture of the planet’s population if this is the case. There could be a lot more Earth-like planets out there. Somewhere out there in the vastness of space, someone is looking up at twin stars and wondering if life will ever evolve with just one sun.