NASA's exoplanet hunter TESS spots a record-breaking 3-star system

Using NASA's exoplanet-hunting spacecraft, the Transiting Exoplanet Survey Satellite (TESS), scientists have spotted a record-breaking triple-star system so tightly bound that it could fit comfortably between the sun and its closest planet, Mercury.

The system, designated TIC 290061484, contains twin stars that race around each other once every 1.8 Earth days as well as a third star that orbits this pair once every 25 Earth days. This triple star system's super-tight orbit, located just under 5,000 light-years away in the constellation Cygnus, the swan, makes it a record-breaker.

The previous record-holder for the tightest three-star system orbit is Lamba Tauri, which set the record in 1956 with its third star taking 33 days to orbit its inner twin stars.

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The discovery team included citizen scientists who met as part of the now-closed Planet Hunters project, which ran from 2010 to 2013. The amateurs joined with professional astronomers to form the Visual Survey Group collaboration, which has been operating for a decade.

"Thanks to the compact, edge-on configuration of the system, we can measure the orbits, masses, sizes and temperatures of its stars," team member Veselin Kostov from NASA's Goddard Space Flight Center and part of the SETI Institute said in a statement. "We can study how the system formed and predict how it may evolve."

Three's company

The team thinks the star system TIC 290061484 is highly stable because the stars orbit each other in nearly the same plane. If the stars' orbits were tilted in different directions, their gravitational influences would disrupt their orbits, making the system unstable.