Galactic discovery: Record find 6.5 bn light-years away using grav lens
Using a natural phenomena called “gravitational lensing”, a team of researchers and astronomers at the University of Arizona’s Steward Observatory have spotted and observed 44 stars in a galaxy about 6.5 billion light-years from Earth, from a time when the universe was half its current age.
Gravitational lensing occurs when light bends around a massive celestial body due to its immense gravity, allowing observation of celestial bodies even more distant from it. The Steward Observatory team used NASA’s James Webb Space Telescope (JWST) to detect 44 individual stars in a galaxy called Dragon Arc, which is in the Earth’s line of sight but beyond a cluster of galaxies called Abell 370. This cluster of galaxies stretched the Dragon Arc’s spiral shape into an elongated one to allow the astronomers to detect its 44 stars in a year from December 2022 and 2023. They found that the brightness of these stars kept changing due to variations in gravitational lensing. The findings are published in the journal Nature Astronomy, recording the largest number of individual stars detected in the distant universe, and opens avenues to more systematically study dark matter, which is one of the biggest mysteries of the universe. Gravitational lens was first discovered by Dennis Walsh, Bob Carswell and Ray Weymann in 1979, naming it the “Twin QSO” as their observation appeared as twin quasi-stellar objects (QSOs). The latest finding reveals that especially with the modernisation in astronomical observation, sensitive telescopes like the JWST can allow detection of distant stars by factors of up to thousands as their light gets amplified due to gravitational lenses. The field of astronomy has suddenly become more exciting than it has ever been as it opens potential to observe more magnified distant stars.