NASA’s TESS probe detects record-breaking stellar triplets

Oct. 2 () –

Allied with artificial intelligence, astronomers have discovered a unique stellar trio called TIC 290061484, thanks to cosmic “strobes” captured by NASA’s TESS satellite.

The system contains a set of twin stars that orbit each other every 1.8 days, and a third star that orbits the pair in just 25 days. The discovery, published in The Astrophysical Journal, breaks the record for the shortest external orbital period for this type of system, set in 1956, when a third star orbited an inner pair in 33 days.

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

Flashes of starlight helped reveal the compact trio, which is located in the constellation Cygnus. It turns out that the system is almost flat from our perspective. This means that the stars pass right in front of, or eclipse, each other as they orbit. When that happens, the closer star blocks some of the light from the farther star.

Using machine learning, scientists sifted through huge TESS starlight data sets to Identify dimming patterns that reveal 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, who are co-authors of the new study, met as participants in an online citizen science project called Planet Hunters, which ran from 2010 to 2013. The volunteers later joined professional astronomers to create a new collaboration called Visual Survey Group, which has been active for more than a decade.

“We are primarily looking for signals from 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 was a co-author of the paper and has 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“. Many more are likely speckling our galaxy, waiting to be discovered.

Partly because the stars in the newly discovered system orbit in nearly the same plane, scientists say it is likely very stable despite its tight configuration (the trio’s orbits fit into an area smaller than Mercury’s orbit around of the Sun). The gravity of each star does not disturb the others too much, as they could if their orbits were tilted in different directions.

But while 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 close to either star.” The exception might be a distant planet that orbits all three stars as if they were one.

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

Meanwhile, astronomers are looking for triple stars with even shorter orbits. That’s hard to do 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 ​​sky covered by a single TESS pixel will fit 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 the stars cluster, providing a sample of the core rather than skimming the entire surface.

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