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An artist’s map of the Milky Way galaxy, with a circle 3,000 light years in radius centered on the Sun. Credit: NASA / JPL-Caltech / Robert Hurt (SSC-Caltech) / Phil Plait (annotation)
Gaia is a European Space Agency mission that orbits the Sun in a stable position about 1.5 million kilometers from Earth. Its mission is to measure the positions, motions, colors, and other characteristics of over
nearly two billion stars in the galaxy. That s it. It doesn t specify what kind of star to look at (other than it has to be bright enough to see) or drill down to answer a specific question.
Multiple stars are just intrinsically cool: Unlike our Sun, sailing alone through space, multiples are where two or more stars orbit each other in a stable, gravitationally bound system. Half the stars in the galaxy are in multiple systems like that. Most are binaries (two stars orbiting each other) and some in trinaries (three stars). Fewer yet are in higher-order systems.
That s the first thing that makes TYC 7037-89-1 special: It s a sextuplet, a six-star system. It s a little over 1,900 light years away, so a fair distance, but it s bright enough to be detected by TESS, the Transiting Exoplanet Survey Satellite. TESS scans the sky measuring the brightnesses of stars to look for transiting exoplanets, which make mini-eclipses on their host stars, revealing their presence.