Astronomers have made an exciting discovery of a unique cosmic formation, identifying a rare cluster of four stars, including three that are larger and hotter than our Sun, all within a space smaller than Mercury's orbit. This remarkable system, named TIC 120362137, features a compact arrangement that is unprecedented in its density.
A Close-Knit Stellar Family
While many stellar systems exist, most are not as tightly packed as this one. Approximately 85% of stellar systems host multiple stars, yet quadruple star formations are exceptionally rare. Before TIC 120362137, only two other compact 3+1 systems had been recorded. Researchers utilized data from NASA's Transiting Exoplanet Survey Satellite (TESS) to identify this intriguing system by detecting periodic brightness dips, which indicated the presence of multiple stars.
Initially, TESS revealed nine brightness changes in a binary star system. Further analysis showed a third star orbiting the pair every 51.3 days, but the complexity of the signals suggested more was happening. The identification of the fourth star was achieved using an advanced algorithm called QUADCOR, which allowed astronomers to isolate the unique spectral signatures of the four stars.
Exploring the Stars
The research team didn't rely solely on TESS data; they conducted a global observational campaign, utilizing telescopes across Hungary, Arizona, the Czech Republic, and Slovakia. This collaborative effort yielded 73 spectra from the Fred L. Whipple Observatory, enabling precise measurements of the stars' masses and sizes, often within a remarkable 1% accuracy.
The three primary stars are incredibly close together, creating a dynamic environment. The heaviest star, designated Aa, has a mass 1.75 times that of the Sun, while its companion Ab weighs 1.36 times as much. The third star, designated B, sits in between at 1.48 solar masses. Meanwhile, the fourth star, C, orbits this trio, completing a full revolution every 1,046 days, which is still closer than Jupiter's distance from our Sun.
While the research team concentrated on star detection, the potential for planets in this system remains uncertain. The extreme heat and luminosity of the three core stars would create an inhospitable environment for life as we know it.
The Significance of TIC 120362137
This stellar configuration is intriguing not only for its rarity but also for its potential to serve as a cosmic laboratory. It provides insights into star formation theories and the future merging of stars into exotic objects, such as white dwarfs. By observing the gravitational interactions between these stars, researchers can refine their understanding of the formation of neutron stars and black hole X-ray binaries, shedding light on the high-energy events that shape our galaxy.
As the stars evolve, they will undergo significant changes. The primary star, Aa, will eventually exhaust its fuel and expand, leading to a complex interplay of materials between the stars. Simulations suggest that this dynamic system may ultimately settle into a quieter state, resulting in a pair of white dwarfs.
The discovery of TIC 120362137 highlights the complexity of the universe and reminds us that our solitary Sun may be the exception rather than the rule, as most stars in our galaxy exist in multiple star systems.