Reviewed by Danielle Ellis, B.Sc.Oct 3 2024
According to a study that was published in The Astrophysical Journal, NASA’s TESS (Transiting Exoplanet Survey Satellite) was able to detect cosmic “strobe lights,” which allowed professional and amateur astronomers to collaborate with artificial intelligence to discover an unparalleled stellar trio known as TIC 290061484.
This artist’s concept illustrates how tightly the three stars in the system called TIC 290061484 orbit each other. If they were placed at the center of our solar system, all the stars’ orbits would be contained a space smaller than Mercury’s orbit around the Sun. The sizes of the triplet stars and the Sun are also to scale. Image Credit: NASA’s Goddard Space Flight Center
The system consists of twin stars that orbit each other every 1.8 days and a third star that circles the pair in just 25 days. The discovery breaks the previous record for the shortest outer orbital period for this type of system, which was set in 1956 when a third star orbited an inner pair in 33 days.
Thanks to the compact, edge-on configuration of the system, we can measure the orbits, masses, sizes, and temperatures of its stars. And we can study how the system formed and predict how it may evolve.
Veselin Kostov, Research Scientist, Goddard Space Flight Center, NASA
Flickers in starlight revealed the tightly knit trio in the constellation Cygnus. The system appears to be nearly flat from our perspective. This means that as they orbit, the stars cross in front of each other, causing an eclipse. When this happens, the nearer star blocks some of the light from the farther star.
Scientists used machine learning to sift through massive sets of TESS starlight data, identifying dimming patterns that revealed eclipses. Then, a small team of citizen scientists filtered further, using years of experience and informal training to identify particularly interesting cases.
These amateur astronomers, who co-authored the new study, met while participating in Planet Hunters, an online citizen science project that ran from 2010 to 2013. The volunteers later collaborated with professional astronomers to form the Visual Survey Group, which has been active for more than ten years.
We are mainly looking for signatures of compact multi-star systems, unusual pulsating stars in binary systems, and weird objects. It is exciting to identify a system like this because they are rarely found, but they may be more common than current tallies suggest.
Saul Rappaport, Study Co-Authors, Emeritus Professor, Physics, Massachusetts Institute of Technology
Scientists believe the newfound system is likely to be very stable, owing to the fact that the stars orbit in nearly the same plane. Each star’s gravity does not cause significant perturbation to the others, as it would if their orbits were tilted differently.
However, while their orbits are expected to remain stable for millions of years, “no one lives here,” Rappaport explained.
Rappaport added, “We think the stars formed together from the same growth process, which would have disrupted planets from forming very closely around any of the stars.”
The exception could 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, resulting in a supernova explosion in approximately 20 to 40 million years.
In the meantime, astronomers are looking for triple stars with even shorter orbits. That is difficult to accomplish with current technology, but a new tool is on its way.
Images from NASA’s upcoming Nancy Grace Roman Space Telescope will be far more detailed than TESS's. The same area of the sky covered by a single TESS pixel can accommodate over 36,000 Roman pixels. And, whereas TESS took a broad, shallow look at the entire sky, Roman will pierce deep into the heart of our galaxy, where stars cluster together, providing a core sample rather than skimming the surface.
We don’t know much about a lot of the stars in the center of the galaxy except for the brightest ones. Roman’s high-resolution view will help us measure light from stars that usually blur together, providing the best look yet at the nature of star systems in our galaxy.
Brian Powell, Study Co-Author and Data Scientist, Goddard Space Flight Center, NASA
Furthermore, Roman will aid astronomers in discovering more triple star systems—systems in which all stars eclipse one another—by tracking light from hundreds of millions of stars as part of one of its primary surveys.
Powell added, “We are curious why we haven’t found star systems like these with even shorter outer orbital periods.”
Roman could discover even larger groups of eclipsing stars, perhaps as many as six or seven, all orbiting one another like bees around a hive.
Roman could also discover eclipsing stars clustered in even bigger groups - six or seven, maybe more - all circling one another like bees circling a hive.
Study Co-Author Tamás Borkovits, a Senior Research Fellow at the Baja Observatory of The University of Szeged in Hungary, added, “Before scientists discovered triply eclipsing triple star systems, we didn’t expect them to be out there. But once we found them, we thought, well why not? Roman, too, may reveal never-before-seen categories of systems and objects that will surprise astronomers.”
TESS Observes Stellar Triplets
Watch how the three stars in the system called TIC 290061484 eclipse each other over about 75 days. The line at the bottom is the plot of the system’s brightness over time, as seen by TESS (Transiting Exoplanet Survey Satellite). The inset shows the system from above. Video Credit: NASA’s Goddard Space Flight Center
Journal Reference:
Kostov, V. B., et. al. (2024) TIC 290061484: A Triply Eclipsing Triple System with the Shortest Known Outer Period of 24.5 Days. The Astrophysical Journal. doi.org/10.3847/1538-4357/ad7368