Although it no longer exists, it would have been created 900 million years after the Big Bang, almost a ‘breath’ after the creation of the Universe
Hubble has revealed incredible images, including the Deep Field, a snapshot that collects 3,000 objects, most of them bright galaxies. In each of them, hundreds of thousands of stars are contained, some of them also individually imaged by the successful space telescope. Now, the ‘old’ Hubble has gone a step further and has managed to observe the most distant single star ever detected. His name is Earendel and his light has taken us 12.9 billion years to arrive.
In fact, Eärendel – whose name will sound familiar to many, since it has been taken from the saga ‘ The Lord of the Rings ‘, written by JRR Tolkien – does not even exist anymore, because it exploded a long time ago.
It was created ‘only’ 900 million years ago, which for the Universe is almost a sigh. “There is a small possibility that it is a first-generation star (the so-called Population III). Although it is most likely a second-generation Population II star, which has been slightly enriched in heavier elements but still has a much lower concentration of heavier elements than current stars,” Brian Welch, a researcher, explains to ABC. from Johns Hopkins University (USA), author of the study that has just been published in ‘ Nature ‘.
With the data obtained by Hubble, the international team has been able to elucidate that Eärendel would have at least 50 times the mass of the Sun, so it would have been much brighter. “These primordial stars (which form from the elements that were forged shortly after the big bang: hydrogen, helium, and small amounts of lithium) have so far eluded observers, but now they could be detected if viewed through gravitational lensing.” high magnification, as in the case of Eärendel,” says Welch.
In other words, it is a star so old that there is some probability that its light belonged to the first stars that were created in the Universe, or that it was very close to them. Because Eärendel’s finding far surpasses the discovery of the farthest star observed so far, Icarus, which was 9 billion light-years away (and was also detected by Hubble).
“The Eärendel star existed in the first billion years of the Universe, during the Big Bang, and its light has traveled 12.9 billion years to reach Earth,” explains José María Diego, a researcher at the Institute of Physics of Cantabria (IFCA, CSIC-UC), which has participated in the study. ‘This find is a huge leap back in time compared to the previous Icarus record; It allows us to go back much further in the origin of the Universe. Eärendel is the farthest star we know of, although it no longer exists. However, we still see the light that comes to us from it. We have been able to detect it thanks to the fact that it is magnified by a cluster of galaxies; if not, it would be impossible to see it”, explains Diego.
Instructions to see a star so far away
As the Universe expands, light from distant objects is stretched or shifted to longer wavelengths as they approach Earth. It is the famous ‘redshift’, which is often compared to the sound of an ambulance when it passes in front of us: its sound is heard stronger or weaker as it approaches or moves away from us. Until now, the objects observed at such a great distance respond to clusters of stars embedded within the first galaxies. And it is very difficult for Hubble to ‘fix’ on just one.
“Normally, at these distances, galaxies are seen as small spots, because the light from millions of stars is mixed,” says Diego. The galaxy that hosts Eärendel has been magnified and distorted by gravitational lensing. Just as curved glass distorts the image when we look through it, a gravitational lens amplifies the light from very distant objects aligned behind a cluster of galaxies. These galaxies are the ones that deflect the light of distant stars because their enormous mass deforms the space-time around them”, explains the researcher.
“Hubble can see the star thanks to the magnifying effect of gravitational lensing. The foreground galaxy cluster bends the space around it, and in doing so causes light from distant objects behind it to bend. In the case of this star, the alignment between the star and the lens group is so precise that it magnifies thousands of times. Earlier lensed stars relied on temporary increases in their magnification from compact objects in the lens group, which occasionally align with images of background stars and increase in magnification over several weeks. In this case, the baseline magnification is much larger and these temporary increases are less pronounced,” says Welch. Namely,
A taste of what James Webb will discover
Early stars are still an unexplored field. And while this Hubble find opens the door to huge discoveries, it is expected to be its successor, the James Webb Space Telescope. whoever takes us further (and earlier) in the observation of the Universe. “In its first year of operations, Webb will provide a spectrum for this object, along with increased infrared wavelength coverage. Together, these data will allow us to more accurately estimate the star’s mass and luminosity and give us a measure of its temperature. Later in the future, Webb’s deeper observations could also tell us what the star is made of and help determine how it formed and how it has evolved.” For his part, Diego points out: «We are going to learn many things: we will obtain the spectrum, that is, the fingerprint of a star, it will tell us how old it is, how long ago it was born, how long it was alive when the light that we see now, its metallicity or the elements that compose it».
And you can also tell us if you have a ‘companion’ who follows you, another of the working hypotheses. At the moment, we cannot determine if it is a binary system and if so, we do not know what the second star would look like. Based on observations of local massive stars, we can infer that it is likely a binary since most massive stars tend to have smaller companions. We assume that the light we see is dominated by one star, and the second star (if it exists) would be much smaller.
This is just the beginning since James Webb will be able to see stars that existed about 13.5 billion years ago (as a fact: the Big Bang is located 13.7 billion years ago), long before Eärendel. An ‘appetizer’ of what is to come in the coming years.
