Two infant stars join into binary system after chance meeting

Astronomers confirmed the pairing of two massive infant stars located 5,300 light-years from Earth in the stellar system IRAS 07299−1651, according to research published on 8 September in the journal Nature Astronomy. The scientists tracked the cosmic movement using the Atacama Large Millimeter/submillimeter Array in Chile.

The stellar encounter occurred approximately 60 years ago.

Observations gathered over eight years demonstrated that the two young bodies did not emerge together from the collapse of a single cloud of gas and dust. Instead, each protostar developed inside its own natal envelope before gravitational pull drew them together during their infancy. Team leader Yichen Zhang of Shanghai Jiao Tong University in China explained the significance of the tracking.

“For the first time, we were able to watch two massive stars move around one another while they were still being born,” Zhang said. The discovery directly challenges traditional models that assume massive binary pairs invariably share a single parent disk.

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Telescopes reveal misaligned disks and chaotic orbits

Researchers initially detected IRAS 07299−1651 in 2019, expecting to measure circular and stable orbital paths. Further analysis revealed eccentric, flattened orbits where the individual dust rings feeding the growing bodies sit tilted at sharp angles against each other.

“It felt like solving a three-dimensional puzzle,” team member Yao Wang of Shanghai Jiao Tong University said. “Each new observation added another piece, and eventually the orbit, disks, and jets all came together into a single, coherent picture.”

Tracing the orbital paths backwards over an eight-year observation baseline with high-precision instruments, researchers discovered that the two protostars approached each other along highly flattened, eccentric paths until gravity forced their separate natal dust clouds into a shared dance. The individual accretion envelopes feeding each object remained distinct despite the close flyby. The disks survived.

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Multiple observatories join forces to map the system

The research team combined radio and infrared data from four major astronomical facilities to construct a complete three-dimensional model of IRAS 07299−1651:

• The Atacama Large Millimeter/submillimeter Array captured high-resolution radio emissions from the inner gas disks.
• The Very Large Array tracked radio signals and the physical shifts of the protostars over time.
• The James Webb Space Telescope delivered infrared imagery penetrating deep dust layers.
• The Very Large Telescope supplied complementary infrared data to determine the orientation of ejected stellar jets.

“Each telescope revealed a different piece of the puzzle,” team member Rubén Fedriani of the Instituto de Astrofísica de Andalucía in Granada said. “The combination of radio and infrared observations provides the most exquisite detail on the formation of this massive protobinary system.”

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The coordinated observations allowed the team to measure how the stars blast high-velocity gas jets into surrounding interstellar territory. These physical structures confirmed that the pair originated in distinct natal environments.

Massive stars dominate galactic environments

Single suns like the one at the center of our solar system represent only part of the stellar population in the Milky Way. Around half of all sun-sized stars belong to multi-star systems, while approximately 90% of massive stars maintain at least one companion.

Massive stars produce heavy chemical elements and terminate their life cycles in supernova explosions that compress surrounding molecular clouds and generate subsequent generations of stars. Understanding how these massive pairs assemble offers direct insight into the wider evolution of host galaxies across cosmic time.

“This study demonstrates that the early lives of stars can be quite chaotic, with a chance encounter leading to this gravitational dance and stellar coupling,” team member Jonathan C. Tan of the University of Technology and the University of Virginia said.

Uncertain future awaits the newborn pair

The long-term survival of the IRAS 07299−1651 pairing remains unresolved because the stars have completed only a small fraction of an orbit since their initial close pass. Gravitational interactions with remaining gas pockets could pull the stars permanently into a tight, bound orbit, or the momentum from their flyby might ultimately separate them back into solitary trajectories.

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Future monitoring with radio arrays will measure whether the orbital eccentricity decreases as the infant stars continue to sweep through the surrounding gas cloud.