NASA announced today an unprecedented discovery made by the Hubble telescope, one that the agency says is worthy of science textbooks. Although tiny to the eye, a mere 3 pixels, it is a huge discovery, for that tiny dot is actually the most distant and oldest star ever observed: Eärendel, 12.9 billion light-years from Earth and formed when the universe was still young, will be a gateway to understanding stellar evolution.
For more than three decades the Hubble Space Telescope has delighted us with countless discoveries, thanks to it we know the age of our Universe since the Big Bang, and have also been able to find images that have led us to the assumption of the existence of dark matter. But this time it has broken its records and NASA announces its most recent record.
What did Hubble discover?
According to the U.S. aerospace agency that operates Hubble in conjunction with ESA, the space telescope has set an extraordinary new benchmark. It succeeded in detecting for the first time the light from a star that existed within the first billion years after the birth of the Universe in the Big Bang. It is the most distant single star ever seen to date.
Although it no longer exists, because it exploded millions of years ago, its light was so powerful that it is still visible and is a record star because, until now, the most distant detected was Icarus, discovered in 2018 at 9 billion light-years.
This is an unprecedented discovery because although human telescopes have been improving with technology, none had been able to capture the light from such an old star. To put it in context, the light from this celestial body took 12.9 billion years to reach Earth, which indicates that its lifetime is exactly 7% of the age of the Universe.
The finding, published today in Nature, was made by an international team led by Brian Welch of Johns Hopkins University (USA) and the Space Telescope Science Institute team.
Why is Eärendel so important?
Eärendel will be “a window into an era of the universe that we are not familiar with, but that led to everything we know. It’s as if we’ve been reading an interesting book, but we started in the second chapter and now we have the opportunity to see how it all began,” said Brian Welch, leader of the team of researchers to the Spanish Consejo Superior de Investigaciones Científicas (CSIC).
The star takes its name from the poem “The Voyage of Eärendel, the Evening Star”, written in 1914 by J.R.R. Tolkien, author of “The Lord of the Rings”, and is located in a galaxy they have named Sunrise Arc.
The team estimates that it would have at least 50 times the mass of the Sun and is much brighter than the Sun, but we will have to wait until the recently launched James Webb telescope is fully operational to determine its mass, size, temperature, radius and to establish whether it is a first or second-generation star.
To predict whether its brightness will be maintained in the coming years or whether it is temporary, “it is necessary to estimate the mass of all the stars in the line of sight,” said Yolanda Jiménez, also a signatory of the research, from the Instituto de Astrofísica de Andalucía (IAA-CSIC), in southern Spain, which has participated in the project.
How Eärendel was found?
The Hubble telescope was designed to see galaxies at the distance of Eärendel, but not to study a single star. However, it has been made possible by a phenomenon called gravitational lensing, the effect of which is like making Hubble 70 times larger.
A gravitational lens is a concentration of very large matter, in this case, a cluster of galaxies so massive that it bends the space around it. As light passes through that area, it bends and acts as a lens.
Looking through that gravitational lens, Hubble magnifies what it sees behind it and, in very small areas, that magnification can be very high, right where Eärendel is.
With information from Ecoosfera and EFE
