NASA’s James Webb Space Telescope has delivered a breakthrough discovery: the rare binary star system Apep, named after the Egyptian god of chaos, is actually a triple system. This revelation, confirmed through new observations, provides unprecedented insight into extreme stellar evolution and the chaotic dynamics of dying stars.
The Peculiar Apep System
Apep consists of two Wolf-Rayet stars — an exceptionally rare class of stars that are massive, hot, and nearing the end of their lives. These stars burn intensely, shedding powerful gas winds as they prepare to explode as supernovas. The scarcity of Wolf-Rayet stars (only around 1,000 exist in our galaxy of hundreds of billions) makes the discovery of a binary system where both stars belong to this category particularly noteworthy.
The new data from Webb confirms the presence of a third companion: a supergiant roughly 40 to 50 times the mass of our sun. The two Wolf-Rayet stars were likely even more massive in their youth, but have since lost mass and now weigh in at 10 and 20 solar masses, respectively.
Layered Dust Shells Reveal Stellar Interactions
What makes Apep truly unique is the way the two Wolf-Rayet stars interact. The telescope’s observations revealed nested dust shells surrounding the system, resembling ripples in a pond. These shells are formed as the two stars approach each other, colliding their gas winds and ejecting carbon dust at speeds of 1,200 to 2,000 miles per second. The shells appear in a consistent pattern, indicating a regular cycle of dust formation over the past 700 years.
Each shell is roughly two light-years across, yet maintains its shape despite outward expansion. Slight warps in the shells suggest either elongated orbits or uneven wind patterns. The third star, orbiting at a greater distance, carves pie-shaped gaps into each shell as it passes through, further confirming its gravitational link to the system.
Distance and Future Research
The observations also suggest that Apep is farther away than previously estimated, perhaps around 15,000 light-years from Earth. The precise distance remains uncertain, requiring further study.
“Looking at Webb’s new observations was like walking into a dark room and switching on the light,” said Yinuo Han, lead author of one of the published papers. “Everything came into view.”
The discovery underscores the power of the James Webb Space Telescope in resolving complex stellar systems and unraveling the mysteries of extreme stellar evolution. The Apep system will continue to be a focal point for astronomers, offering valuable insights into the final stages of massive stars.
