The Hubble Space Telescope peeked into the dawn of the cosmic age and discovered the light of a star that existed within the first billion years after the Big Bang which is a new record, astronomers announced on Wednesday.
The newly discovered star, called “Earendel”, is so far away that it took its light 12.9 billion years to reach Earth from the time when the universe was seven percent of its current age.
“At first we almost didn’t believe it, it was much further than the furthest before,” said astronomer Brian Welch of Johns Hopkins University in Baltimore, lead author of a paper in Nature describing the discovery.
The previous ‘record holder’ was discovered in 2018 when the universe was four billion years old.
As the universe expands, the moment the light of distant stars reaches us, it is stretched to longer, redder wavelengths, a phenomenon called “redshift”.
Earendel’s light comes from an era called redshift 6.2.
“Usually at these distances, entire galaxies look like small spots, and the light of millions of stars merges,” Welch said in a statement.
The galaxy in which the star is located is naturally enlarged and distorted by the effect of the so-called. gravitational lenses, a group of galaxies located between a distant light source and an observer and their gravitational field bend light to create images such as a ring.
The cosmic ‘magnifier’ in this case is a huge group of galaxies known as WHL0137-08, which, thanks to sparse alignment, provides maximum magnification and illumination.
“The galaxy in which this star is located has been magnified and distorted by gravitational lenses into a long crescent that we have called the Arc of Sunrise,” Welch said.
After studying the galaxy in detail, Welch discovered that one feature was actually an extremely magnified star he named Earendel, which means “morning star” in Old English.
Earendel existed so long ago that it may not have had the same raw materials as the stars that exist today, Welch added.
“It’s like reading a really interesting book, but we started with the second chapter, and now we’re going to have a chance to see how it all started,” he said.
Astronomers plan to observe the star using the James Webb Space Telescope, Hubble’s successor, which is very sensitive to infrared light from the oldest celestial bodies, to confirm Earendel’s age, mass and radius.
Scientists say that if Earendel is confirmed to be a single star, its mass is at least 50 times larger than the Sun and millions of times brighter.
It is assumed that primordial stars are composed exclusively of elements created after the Big Bang: hydrogen, helium and trace lithium, and should be heavier than the stars that exist today.
It remains to be seen whether Earendel belongs to these “Population III” stars, but while the likelihood is small, it is tempting, Welch said.
Webb, who is set to go online this summer, is expected to break Hubble’s records and peek even further into the past.
Scientists expect Earendel to remain magnified for years and will continue to be studied using NASA’s Webb Space Telescope.