Looking for Earth 2.0 in binary systems
While astronomers have found thousands of exoplanets over the last few decades, the true prize continues to elude them—they have yet to find an Earth-mass, rocky planet orbiting in the habitable zone of a sun-like star. That's partially due to cosmic geography—around half of all sun-like stars near us aren't alone. They have one or more companion stars that complicate their orbital dynamics, as…
Scientists have yet to discover an Earth-mass, rocky planet in the habitable zone of a sun-like star. Around half of the sun-like stars near us have companion stars, which complicates the search for exoplanets in these multistar systems. Currently, three main methods are used to hunt for exoplanets: transiting, radial velocity, and astrometry.
Transiting and radial velocity have limitations, making astrometry the most promising approach. Astrometry measures the exact position of stars against a background field of stars, but sensitivity issues have hindered progress. The new NASA Small Explorer mission SHERA aims to use astrometry in a novel way. Instead of mapping a star against the background, SHERA focuses on bright, closely separated binary pairs of stars.
These binaries act as co-moving reference points, eliminating background error and canceling out large-scale optical distortions. To achieve the required sub-microarcsecond precision, SHERA uses a diffractive pupil created through electron-beam lithography. The mission will search for Earth-mass planets around the closest target stars, test the suppression of planet formation in close-in binaries, and provide additional context to ground-based radial velocity data.
If successful, SHERA could significantly contribute to the Habitable Worlds Observatory, a more expensive mission targeting these stars.
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- Looking for Earth 2.0 in Binary Systems universetoday.com
