Comments:50 pages, 11 figures (3 main text, 8 extended data). Published in Nature
Journal-ref:Nature 603, 815-818 (2022)
Subjects:Astrophysics of Galaxies (astro-ph.GA)
Galaxy clusters magnify background objects through strong gravitational lensing. Typical magnifications for lensed galaxies are factors of a few but can also be as high as tens or hundreds, stretching galaxies into giant arcs. Individual stars can attain even higher magnifications given fortuitous alignment with the lensing cluster. Recently, several individual stars at redshiftz∼1−1.5have been discovered, magnified by factors of thousands, temporarily boosted by microlensing. Here we report observations of a more distant and persistent magnified star at redshiftzphot=6.2±0.1, 900 Myr after the Big Bang. This star is magnified by a factor of thousands by the foreground galaxy cluster lens WHL0137--08 (z=0.566), as estimated by four independent lens models. Unlike previous lensed stars, the magnification and observed brightness (AB mag 27.2) have remained roughly constant over 3.5 years of imaging and follow-up. The delensed absolute UV magnitudeMUV=−10±2is consistent with a star of massM>50M⊙. Confirmation and spectral classification are forthcoming from approved observations with the James Webb Space Telescope
