admin Astronomers from the Indian Institute of Astrophysics (IIA) have made an extraordinary discovery. They identified a vampire star in the star cluster M67, located in the constellation Cancer. This discovery, using data from the UltraViolet Imaging Telescope on board AstroSat, India’s first dedicated space observatory, marks a significant advancement in astrophysical research.
The vampire star, named WOCS 9005, is rejuvenating by siphoning material from a companion star. This process, known as mass transfer in a binary system, rejuvenates the star, making it appear younger than its age. The star cluster M67, which is a loosely gravitationally bound grouping of over 500 stars, provided the perfect environment for such a discovery.
Using spectroscopy, a technique where starlight is dispersed into its colors, the team studied WOCS 9005’s surface composition. The results were surprising. While this star was expected to have a chemical composition similar to our Sun, it showed an atmosphere rich in heavy elements like barium, yttrium, and lanthanum. These elements are typically found in asymptotic giant branch (AGB) stars, which are more massive and evolved than WOCS 9005. However, the presence of these heavy elements in WOCS 9005’s atmosphere suggested a different story.
The presence of heavy elements indicated a polluted atmosphere, with the source likely being an external companion star. This companion, after passing through its AGB phase, became a white dwarf and transferred its heavy elements to WOCS 9005. The astronomers confirmed this by analyzing the star’s ultraviolet (UV) brightness, which was higher than expected for a star with a temperature similar to the Sun.
This unexpected UV brightness was traced back to WOCS 9005’s hot, small companion, supporting the mass transfer theory. The researchers also conducted theoretical calculations to validate their findings, confirming that the vampire star is indeed the remnant of a star that once produced these heavy elements.
This discovery not only sheds light on the complex processes of stellar evolution but also opens new avenues for studying the lifecycle of stars in binary systems. The findings will be published in The Astrophysical Journal Letters, contributing to our understanding of the intricate dance of stars in the universe.
Magazine 
