An international team with the participation of CSIC researchers has detected Eärendel, the most distant star ever observedlocated 12.9 billion light-years from Earth. Land. The star no longer exists, it exploded millions of years ago, but its light was so powerful that it is still visible.
Eärendel, the farthest star ever observed
Eärendel, which existed when the universe was young, just a billion years following the big bang (which occurred 13.8 billion years ago), was much more massive and brighter than the Sun. Its discovery opens a window to learn regarding the early days of the Universe and the origin of the first star formations. The results are published in the journal Nature.
Eärendel’s discovery far exceeds the finding of the farthest star observed to date: Icarus, detected in 2018 by the Hubble Space Telescope at 9,000 million light-years.
“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 the researcher Jose Maria Diegofrom the Institute of Physics of Cantabria (IFCA, CSIC-UC), which has participated in the study, led by Brian Welchfrom Johns Hopkins University (USA), and the team Space Telescope Science Institute (STScI).
The star gets its name from the poem The journey of Eärendel, the evening starwritten in 1914 by John Ronald Reuel Tolkien, author of The Lord of the ringswhich was inspired by Anglo-Saxon mythology. “This find is a huge leap back in time compared to the previous Icarus record; allows us to go back much further in the origin of the Universe”Add.
“Eärendel is the most distant star we know of, although it no longer exists. It’s very bright, but it blew up a long time ago. 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”Diego explains.
A star magnified by gravitational lensing
As the Universe expands, light from distant objects is stretched or displaces at longer wavelengths as they approach Earth. Until now, the objects observed at such a great distance respond to clusters of stars embedded within the first galaxies.
“Normally, at these distances, galaxies are seen as small spots, because the light of millions of stars is mixed”says Diego. “The galaxy that hosts Eärendel has been magnified and distorted by gravitational lensing”details. “Just as a curved glass distorts the image when we look through ita gravitational lens amplifies light from very distant objects and aligned behind a cluster of galaxies. These galaxies are the ones that deflect the light of distant stars because their enormous mass warps the space-time around them.explains the researcher.
The team estimates that Eärendel would have at least 50 times the mass of the Sun and that it would be much brighter than this, thus rivaling the most massive known stars. “These primordial stars (which form from the elements that were forged shortly following the big bang: hydrogen, helium, and small amounts of lithium) have so far eluded observers, but now they might be detected if viewed through gravitational lensing. of high magnification, as in the case of Eärendel”Welch comments.
This discovery marks the opening of a new era of very early star formation, still unexplored. “These stars are first generation and we hardly knew anything regarding them. From now on, with stars like this, we will be able to study them in detail with telescopes like the James Webb. In fact, there is already an observation program approved by NASA and in which we participate”Add.
Earendel’s study
“Studying Eärendel will be a window into an era of the Universe that we are not familiar with, but which led to everything we know. It is as if we have been reading an interesting book, but we start in the second chapter and now we have the opportunity to see how it all began.completa Brian Welch.
The researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) Yolanda Jimenez Tejawho has participated in the project, explains that “To predict whether Eärendel will stay bright for years to come or if it is temporary, we need to estimate the mass of all the stars that are in the line of sight between us and Eärendel”. Since the data indicates that the brightness of the star will continue for years, the next step would be to study it with the space telescope. James Webb.
The great contribution of James Webb
Astronomers expect that by 2022 Eärendel will be seen to be increasingly enlarged with the telescope James Webb, launched at the end of 2021 and led by the North American, European and Canadian space agencies (NASA/ESA/CSA). “Webb’s images and spectra will allow us to confirm that Eärendel is indeed a star and narrow down its age, temperature, mass and radius.”Diego explains.
For his part, lead researcher Brian Welch says that “Combining the Hubble and Webb observations will also allow us to learn regarding microlensing in the galaxy cluster, which might include exotic objects such as primordial black holes”.
In addition, with the telescope it will be possible to know more regarding the composition of this star, a subject of special interest to astronomers because it was formed before the Universe was filled with heavy elements, produced by several generations of massive stars. “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 we see now was emitted, its metallicity or the elements that compose it”Diego points out.
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Source: CSIC Communication
Reference article: https://www.csic.es/es/actualidad-del-csic/el-telescopio-hubble-detecta-earendel-la-estrella-mas-lejana-jamas-observada
