BLUE STRAGGLER
1. About
- In general a bunch of stars are born at the same time from the same cloud that forms a star cluster.
- As time passes, each star evolves differently depending on its mass.
- The most massive and bright stars evolve and move off the main sequence creating a bend in their track, known as the turnoff.
- Stars above this bend or brighter and hotter stars are not expected in a cluster, as they leave the main sequence to become red giants.
- But in 1953, Allan Sandage found that some stars seem to be hotter than the turnoff of the parent cluster.
- Initially, these blue stars, still straggling above the turnoff, were not part of these clusters.
- However, later studies confirmed that these stars are indeed cluster members, and they were termed “Blue Stragglers”.
2. Indian Research on Blue straggler
- Indian researchers have found that:
- Half of the blue stragglers are formed through mass transfer from a close binary companion star.
- One third are likely formed through collisions of two stars.
- Remains are formed through interactions of more than two stars.
3. Importance of the Study
- The study will help improve understanding of these stellar systems to uncover exciting results in studies of large stellar populations, including galaxies.
- Following these findings, the researchers are conducting detailed analyses of individual blue stragglers in the catalogue to obtain their stellar properties.
- Furthermore, interesting clusters and blue stragglers identified in this study will be followed up with an ultraviolet imaging Telescope on AstroSat, India’s first dedicated space observatory, as well as the 3.6 m Devasthal Optical Telescope in Nainital.
