A Stellar Family Portrait: Astronomers Discover the Most Crowded Star System Yet
Imagine three suns, each larger and hotter than our own, crammed into a space smaller than Mercury’s orbit. Now picture a fourth, sun-like star circling this chaotic trio. This isn’t science fiction; it’s the reality of TIC 120362137, a newly discovered quadruple star system that’s rewriting our understanding of stellar configurations.
The Rarity of Four-Star Systems
While many stars exist in pairs or even larger groupings, quadruple star systems are exceptionally rare. Researchers estimate that up to 85% of stars have more than one companion, but confirming these systems, especially those with four stars, is a significant challenge. Of the roughly 101 potential quadruple candidates identified in recent data, TIC 120362137 stands out as the most compact 3+1 system ever observed.
How Was This System Discovered?
The discovery relied on data from NASA’s Transiting Exoplanet Survey Satellite (TESS), which monitors the brightness of stars for dips indicating orbiting planets. In this case, TESS detected nine brightness dips in a binary star system. Further analysis, incorporating Eclipse Timing Variations (ETV) – rhythmic shifts in the binary’s timing – revealed a third orbiting star. However, irregularities in the orbits hinted at a fourth, hidden component.
The key to unlocking the system’s secrets was an algorithm called QUADCOR, which isolated the unique spectral fingerprints of all four stars simultaneously. This allowed astronomers to transform a complex signal into a precise measurement of the system’s components.
Meet the Stars of TIC 120362137
The team utilized telescopes in Hungary, Arizona, the Czech Republic and Slovakia, gathering 73 spectra from the Whipple Observatory in Arizona alone. This data allowed for incredibly precise calculations of the stars’ masses and sizes.
The three “core” stars are tightly packed. Star Aa, the most massive, is 1.75 times the mass of our Sun. Its companion, Ab, is 1.36 solar masses, while Star B weighs in at 1.48 solar masses. These three stars reside within a space smaller than Mercury’s orbit around our Sun.
Orbiting this trio is Star C, roughly the same mass and temperature as our Sun, completing a lap every 1,046 days – still closer to the central stars than Jupiter is to our Sun.
Why This Discovery Matters
Systems like TIC 120362137 are gravitationally unstable and rare, requiring a delicate balance to avoid disintegration. However, they offer invaluable insights into star formation and the evolution of stellar systems. They serve as “stress tests” for our theories and can eventually merge into exotic objects like white dwarfs.
A Glimpse into the Future
The future of TIC 120362137 is likely to be dramatic. The primary star, Aa, will eventually expand, spilling material onto its companions and potentially leading to mergers. Simulations predict the system will ultimately settle into a pair of white dwarfs.
This discovery challenges the notion that our solar system is typical. Most stars in the galaxy have companions, and systems as tightly packed as TIC 120362137 suggest that complex stellar arrangements are more common than previously thought.
Frequently Asked Questions
What is a quadruple star system?
A quadruple star system consists of four stars gravitationally bound to each other.
How rare is a system like TIC 120362137?
Extremely rare. It’s the most compact 3+1 quadruple star system discovered to date.
Could planets exist in this system?
While not yet known, the chaotic environment and frequent eclipses would make it extremely challenging for planets to form or sustain life.
What will happen to this system in the future?
The system is predicted to eventually evolve into a pair of white dwarfs after a period of stellar expansion and mergers.
Journal Reference: Discovery of the most compact 3+1-type quadruple star system TIC 120362137. DOI 10.1038/s41467-026-69223-4