On January 14, 2025, astronomers utilizing the Hubble Space Telescope announced the discovery of an unusual star system known as the "Blue Lurker" within the M67 star cluster. This system exhibits unique characteristics resulting from complex interactions among three stars.
The "Blue Lurker" resembles the Sun but rotates significantly faster, completing one rotation in four days compared to the typical thirty days. This finding was made possible through observations from the Kepler Space Telescope.
Emily Liner from the Illinois Institute of Technology explains that the formation history of this system is quite extraordinary. Approximately 500 million years ago, two stars in a binary system merged, leading to the formation of a massive star. This star subsequently expanded into a giant and transferred some of its mass to the "Lurker," significantly accelerating its rotation.
Currently, the "Blue Lurker" orbits a white dwarf, which is the remnant of the massive star. Hubble's ultraviolet observations revealed that the temperature of the white dwarf reaches 23,000 degrees Fahrenheit, three times the surface temperature of the Sun, with a mass of 0.72 solar masses, exceeding the expected 0.5 solar masses for white dwarfs in M67.
According to Liner, this is one of the few triple systems whose evolution can be described in such detail. Triple star systems, which make up about 10% of stars similar to the Sun, may play a significant role in the formation of unusual cosmic objects.