Top News

This 4-star system lies 82 light-years away: What's so special?
20 Aug 2025

Astronomers have discovered a rare hierarchical quadruple star system that could help unlock the mystery of brown dwarfs.

The system, located 82 light-years away from Earth in the constellation Antlia, consists of two cold brown dwarfs orbiting two young red dwarf stars.

The discovery was made by an international team led by Professor Zenghua Zhang from Nanjing University and published in the Monthly Notices of the Royal Astronomical Society.

Hierarchical structure of the system
Orbital characteristics

The system, dubbed UPM J1040-3551 AabBab, is unique because of its hierarchical structure.

This means that the two pairs of stars (Aab and Bab) orbit each other separately for decades, while also orbiting a common center of mass over more than 100,000 years.

The two pairs are separated by a whopping 1,656 astronomical units (AU), where one AU is the distance between Earth and Sun.

Composition of the pairs
Stellar composition

The brighter pair in this system, UPM J1040-3551 Aab, consists of two nearly equal-mass red dwarf stars that appear orange in visible wavelengths.

They are about 100,000 times fainter than Polaris (the North Star) in visible wavelengths.

The fainter pair, UPM J1040-3551 Bab, consists of two cooler brown dwarfs that emit virtually no visible light and are about 1,000 times dimmer than their brighter counterparts when viewed in near-infrared wavelengths.

Spectroscopic observations
Data collection

Dr. Felipe Navarete from the Brazilian National Astrophysics Laboratory led the spectroscopic observations that helped characterize the system's components.

He obtained optical spectra of the brighter pair with Goodman spectrograph on Southern Astrophysical Research (SOAR) Telescope in Chile, and near-infrared spectra of fainter pair with SOAR's TripleSpec instrument.

Their analysis revealed both components of the brighter pair are M-type red dwarfs with temperatures around 2,926 degree Celsius and masses about 17% that of our Sun.

What are brown dwarfs?
Stellar evolution

Brown dwarfs are small, dense low-mass objects that are too big to be considered planet but too small to be a star. They lack the mass required for continuous nuclear fusion and transformation into fully-fledged stars.

The brown dwarfs in this system are similar in size to Jupiter but have masses 10-30 times greater.

This discovery is first of its kind with a pair of T-type brown dwarfs orbiting two stars, providing an unprecedented opportunity for studying these elusive objects.

Breakthrough in understanding brown dwarfs
Research potential

The discovery of the UPM J1040-3551 system is a major step forward in understanding these elusive objects and their formation paths.

Professor Hugh Jones from the University of Hertfordshire said, "Brown dwarfs with wide stellar companions whose ages can be determined independently are invaluable at breaking this degeneracy as age benchmarks."