Astronomers discover formation of Blue Straggler Star
In an international collaboration, astronomers from Indian Institute of Astrophysics (IIA), along with their counterparts from India, Italy, France and the U.S., have discovered the
In an international collaboration, astronomers from Indian Institute of Astrophysics (IIA), along with their counterparts from India, Italy, France and the U.S., have discovered the formation of a Blue Straggler Star (BSS) whose origin and evolution has long puzzled astronomers. Peculiar class The BSS is a peculiar class of stars found in star clusters that appear hotter, brighter and more massive than their peers, and in a study published in the Astrophysical Journal Letters astronomers have provided direct evidence of how such stars are created. “The most widely accepted explanation is that these stars gain mass from a companion or through stellar mergers, effectively rejuvenating themselves. Yet, direct observational evidence of such formation processes has remained extremely rare,” said the Department of Science and Technology (DST).
To investigate this, the IIA astronomers studied a binary star system TIC 327546480 in the old open star cluster Collinder 261, located about 9,500 light-years away. The system was identified as a promising candidate for further investigation since its properties suggested ongoing interaction between the two stars. The DST said the study combined high-precision light curves from NASA’s TESS space mission with radial velocity measurements obtained using the Very Large Telescope operated by the European Southern Observatory in Chile. Gaining material “We discovered that the Blue Straggler Star is actively gaining material from its companion star, providing a rare glimpse of a BSS caught in the act of formation. Our finding offers direct observational evidence for one of the leading theories proposed to explain the origin of the BSS,” said Annapurni Subramaniam, faculty member at the IIA and a co-author of the study.
The DST added that the team also found the binary system to be semidetached, meaning that one of the two stars has expanded enough to overflow its gravitational boundary, known as the Roche lobe, causing the less massive companion star to transfer matter to the BSS. “This ongoing mass transfer from the less massive companion to the BSS confirms that the rejuvenation process is still taking place, making the system one of the clearest examples of a forming blue straggler identified so far,” it said. The researchers also detected strong “Detailed analysis showed that the BSS has a mass of about 1.67 times that of the Sun and is accreting matter from a companion with a mass of about 0.32 solar mass.
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