NASA’s TESS Discovers Record-Breaking Triple Star System.

This artist’s concept depicts the tight orbits of the three stars in TIC 290061484, fitting within a space smaller than Mercury’s orbit if placed at the center of our solar system, with star sizes shown to scale alongside the Sun.

Professional and amateur astronomers collaborated with artificial intelligence to discover an unprecedented stellar trio known as TIC 290061484, utilizing data from NASA’s TESS (Transiting Exoplanet Survey Satellite) that detected cosmic “strobe lights.” This system features a pair of twin stars orbiting each other every 1.8 days, accompanied by a third star that orbits the pair in just 25 days. This discovery sets a new record for the shortest outer orbital period in such systems, surpassing the previous record of 33 days established in 1956.

Thanks to the compact, edge-on configuration of the system, we can measure the orbits, masses, sizes, and temperatures of its stars, stated Veselin Kostov, a research scientist at NASA’s Goddard Space Flight Center and the SETI Institute. This allows us to study how the system formed and predict its future evolution.The findings, led by Kostov, were published in The Astrophysical Journal on October 2.

Flickers in starlight unveiled a compact trio of stars in the constellation Cygnus, with their nearly flat alignment allowing them to eclipse each other as they orbit. This configuration leads to one star blocking some light from another during these eclipses. Utilizing machine learning, scientists sifted through vast amounts of starlight data from TESS to identify dimming patterns indicative of these eclipses. A small group of citizen scientists, who gained experience through the Planet Hunters project from 2010 to 2013, collaborated with professional astronomers to form the Visual Survey Group, dedicated to discovering unique stellar systems.

“We focus on signatures of compact multi-star systems, unusual pulsating stars, and other anomalies,” said Saul Rappaport, an emeritus physics professor at MIT and co-author of the study. “Finding a system like this is thrilling, as they’re rare but may be more common than we realize.” The stability of this trio, with orbits fitting within a smaller area than Mercury’s, suggests minimal gravitational disruption between the stars.

While their orbits are expected to remain stable for millions of years, Rappaport notes, “no one lives here.” The stars likely formed together, disrupting the formation of close-in planets, though a distant planet could orbit the trio. As the inner stars evolve, they will eventually expand and merge, leading to a supernova explosion in about 20 to 40 million years. In the meantime, astronomers continue their search for triple star systems with even shorter orbits, a challenging endeavor with current technology, but promising advancements are on the horizon.

This graphic illustrates the search areas of three transit-spotting missions: NASA’s upcoming Nancy Grace Roman Space Telescope, TESS, and the retired Kepler Space Telescope, highlighting that Kepler found 13 triply eclipsing triple star systems, TESS has identified over 100, and Roman is expected to discover more than 1,000.

Images from NASA’s upcoming Nancy Grace Roman Space Telescope will provide far more detail than those from TESS, as a single TESS pixel corresponds to over 36,000 Roman pixels. While TESS conducted a wide survey of the sky, Roman will delve deep into the heart of our galaxy, offering a focused view of densely packed stars.

“We currently know little about most stars at the galaxy’s center, aside from the brightest ones,” said Brian Powell, a data scientist at Goddard and co-author of the study. “Roman’s high-resolution imagery will allow us to measure light from stars that typically blur together, giving us the clearest insight into star systems in our galaxy.”

As Roman monitors light from hundreds of millions of stars, it aims to uncover more triple star systems where all stars eclipse each other. “We’re curious why we haven’t found systems with even shorter outer orbital periods,” Powell noted. “Roman could help us identify them and understand their limits.”

Additionally, Roman may discover eclipsing stars within larger groups, potentially revealing systems with six or more stars orbiting together. “Before the discovery of triply eclipsing triple star systems, we didn’t expect them to exist,” said co-author Tamás Borkovits, a senior research fellow at the Baja Observatory. “Roman may uncover entirely new categories of stellar systems that will surprise astronomers.”

TESS is managed by NASA Goddard and operated by MIT, with support from multiple partners, including Northrop Grumman and NASA’s Ames Research Center. NASA’s citizen science initiatives enable public involvement in scientific discoveries, inviting volunteers to participate without citizenship requirements. For more information, visit NASA’s Citizen Science page.