New three-star system sets record for shortest orbital period

Professional and amateur astronomers have made a groundbreaking discovery with the help of artificial intelligence, identifying a unique triple star system named TIC 290061484. This stellar trio was discovered using cosmic “strobe lights” observed by the NASA’s Transiting Exoplanet Survey Satellite (TESS).

TIC 290061484 features a pair of twin stars that orbit each other every 1.8 days, as well as a third star that orbits the duo in just 25 days. This remarkable discovery breaks the previous record for the shortest outer orbital period in such systems, set in 1956 with a third star orbiting an inner pair in 33 days.

“Thanks to the system’s compact, cutting-edge configuration, we can measure the orbits, masses, sizes and temperatures of its stars,” said Veselin Kostov, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, in Maryland, and the SETI Institute in Mountain View, California. “And we can study how the system formed and predict how it might evolve.”

A paper, led by Kostov, describing the results was published in The Astrophysics Journal October 2.

The twinkles of starlight helped reveal the tight trio, located in the constellation Cygnus. The system turns out to be almost flat from our point of view. This means that the stars each pass each other directly in front of each other or eclipse each other during their orbit. When this happens, the closer star blocks some of the light from the farther star.

Using machine learning, scientists filtered huge starlight datasets from TESS to identify attenuation patterns revealing eclipses. Then a small team of citizen scientists filtered further, drawing on years of experience and informal training to find particularly interesting cases.

These amateur astronomers, co-authors of the new study, met as participants in an online citizen science project called Planet Hunters, active from 2010 to 2013. The volunteers then teamed up with professional astronomers to create a new collaboration called the Visual Survey Group, active for over a decade.

“We mainly look for signatures of compact multi-star systems, unusual pulsating stars in binary systems and strange objects,” said Saul Rappaport, professor emeritus of physics at MIT in Cambridge. Rappaport co-authored the paper and helped lead the Visual Survey Group for more than a decade. “It’s exciting to identify a system like this because they are rarely found, but they may be more common than current counts suggest.” It is likely that there are many other spots speckling our galaxy, waiting to be discovered.

Partly because the new system’s stars orbit in nearly the same plane, scientists say it is likely very stable despite their narrow configuration (the trio’s orbits fit into an area smaller than Mercury’s orbit around of the sun). Each star’s gravity doesn’t disrupt the others too much, as they might if their orbits were tilted in different directions.

But even though their orbits will likely remain stable for millions of years, “nobody lives here,” Rappaport said. “We think the stars formed together from the same growth process, which would have prevented planets from forming very closely around any of the stars.” The exception might be a distant planet orbiting all three stars as if they were one.

As the inner stars age, they expand and eventually merge, triggering a supernova explosion in about 20 to 40 million years.

Meanwhile, astronomers are searching for triple stars with even shorter orbits. This is difficult to achieve with current technology, but a new tool is on the way.

Images from NASA’s upcoming Nancy Grace Roman Space Telescope will be much more detailed than those from TESS. The same area of ​​the sky covered by a single TESS pixel will correspond to more than 36,000 Roman pixels. And while TESS took a broad, shallow look at the entire sky, Roman will drill deep into the heart of our galaxy, where stars gather, providing a core sample rather than skimming the entire surface.

“We don’t know much about most of the stars in the center of the galaxy, except for the brightest ones,” said Brian Powell, co-author and data scientist at Goddard. “Roman’s high-resolution view will help us measure light from stars that are usually out of focus, providing the best insight into the nature of star systems in our galaxy.”

And since Roman will monitor the light of hundreds of millions of stars as one of his major studies, it will help astronomers find more triple star systems in which all the stars eclipse each other.

“We’re curious why we haven’t found star systems like these with even shorter outer orbital periods,” Powell said. “Roman should help us find them and bring us closer to discovering their limits.”

Roman might also find eclipsing stars linked together in even larger groups – half a dozen or more, all orbiting each other like bees buzzing around a hive.

“Before scientists discovered triple-eclipsing triple star systems, we didn’t expect them to exist,” said co-author Tamás Borkovits, principal investigator at the University’s Baja Observatory. from Szeged in Hungary. “But once we found them, we said: why not? Roman could also reveal previously unseen categories of systems and objects that will surprise astronomers.”