HUBBLE SPOTS ITS MOST DISTANT STAR YET

Meet Earendel, a star whose light took 12.8 billion years to reach Earth

- Charles Q. Choi

The most distant single star yet dates back to less than 1 billion years after the universe's birth in the Big Bang and may shed light on the earliest stars. Scientists nicknamed the star 'Earendel', from an Old English word meaning 'morning star' or 'rising light'. Earendel, technical designation WHL0137-LS, is at least 50 times the mass of the Sun and millions of times as bright.

This newfound star is so far away that its light has taken 12.8 billion years to reach Earth, appearing to us as it was when the universe was about 900 million years old, just seven percent of its current age. Until now, the most distant single star detected, discovered by Hubble in 2018, existed when the universe was about 4 billion years old, or 30 percent of its current age. "This finding gives us an opportunity to study a star in detail in the early universe," said lead scientist Brian Welch, an astrophysicist at Johns Hopkins University in Baltimore.

Even a star as brilliant as Earendel would usually be impossible to see from Earth given the vast divide. Previously, the smallest objects seen at such great distances were clusters of stars embedded in early galaxies. Scientists detected Earendel with the help of a huge galaxy cluster, WHL0137-08, sitting between Earth and the star. The gravitational pull of this enormous cluster warped the fabric of space-time, resulting in a powerful natural magnifying glass that greatly amplified the light from objects behind the galaxy. This gravitational lensing has distorted the light from the galaxy hosting Earendel into a long crescent researchers named the Sunrise Arc.