James-Webb looks into Earendel, the most distant known star

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[EN VIDÉO] Understand the James Webb Space Telescope mission in a minute
The James Webb Space Telescope, a new flagship in space observation, will be launched on December 18 from Kourou, Guyana. After a journey of 29 days, it will reach the Lagrange point L2 in the opposite direction from the Sun. With its mirror larger than Hubble, to which it is considered the successor, JWST will be able to observe galaxies, planets, nebulae and stars to learn more about the history of the universe.

We have undoubtedly entered the era of the James Webb Space Telescope (JWST), and it promises to be even brighter than that which opened thirty years ago with the Hubble telescope.. In particular, we expect JWST to shed some light on what happened shortly after the end of the dark ages followed by the “cosmic rebirth”, also calledDawn cosmic, which is the epoch of re-ionization (EoR), when powerful light sources – whose origin is not yet known with certainty – began to re-ionize atoms neutrals that had formed over a few thousand years, about 380,000 years after big bang.

Astronomer Michelle Thaller explains to us in this video what Cosmic Dawn is, a period of re-ionization that will make it possible to study James-Webb and not just him. For a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then be displayed. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Select “French”. © NASA Goddard Space Flight Center

The exact date of the beginning of re-ionization is a matter of debate, and all that can be said is that it occurred between 100 and 400 million years after big bang. Before, at the very beginning, no star existed yet, but during the EoR there is reason to believe that those that formed and shone were very massive, at least 50 to 100 million years old. plenty solar power. We are talking about these stars with respect to stars of people IIIjust as a 3 month old baby is older than a 1 month old baby.

An almost population III star?

That theory of evolution stars tell us that these stars lived at most a million years and produced nucleosynthesis star for the first time inUniverse observable nuclei heavier than lithiumwhich they will then spread to the children cosmos by exploding as a supernova. Thereby they will change the composition of clouds where new stars can be born from collapse gravity, which subsequently favors the appearance of less massive stars, so that more than a billion years after the Big Bang, it has become impossible to observe stars with all the characteristics of those in population III.

Astronomer Michelle Thaller’s explanations of population III stars and Earendel. © Space.com

However, it is possible that the star at the record distance discovered recently with hubble telescope and as Futura had discussed in some detail in the previous article below, Earendel, either one of the last population III stars born less than a billion years after the Big Bang (or at least very similar to them), or much more likely , as explained byastronomer Michelle Thaller, unfortunately in English in the video above, an example of stars with very little difference in composition and properties, born right after them.

Remember she was only flushed out using one gravitational lensthe magnifying effect (in this case by a factor of at least 1,000) caused by the gravitational field in a a cluster of galaxies intervening between Earendel and Hubble, deflecting light rays like a magnifying glass.

Calculations then showed that Earendel must contain at least 50 solar masses, and that it was observed when the universe was only about 900 million years old.

Recently, the first image showing Earendel was uploaded Twitter.

Hubble breaks all records for the most distant star ever observed

Article by Laurent Sacco published on 03/04/2022

that Hubble Space Telescope has just shown that we could always count on him setting a distance record for stars in the distant universe before the commissioning of the James-Webb telescope. That Nasa has just announced that he had imaged the most distant star yet known as it was 12.9 billion years ago.

Her name is Ear part and one would think that it is a variation of the name ofEarendilone of the Elvish characters created by the British author JRR Tolkien and mentioned in Lord of the Rings. However, NASA explains that it is an old English term meaning ” morning star “. But for us, above all, it is a star that was observed when the universe was only 7% of its age, meaning that photons which was collected with the Hubble telescope, it took 12.9 billion years to reach it.

The most distant star known to date

It is actually the most distant star ever discovered to date, and like some of the distant galaxies that in its day broke distance records thanks to the Hubble telescope, astrophysicists made use of the gravitational lensing effect of a significant mass distribution to create an additional zoom that this alone could not eye in orbit around the noosphere. In this case, it was the WHL0137-08 cluster of galaxies that broke the previous record for a solitary star. In fact, Hubble had then managed to see into a time when the observable cosmos was only 4 billion years old.

Video taken from the documentary The Odyssey of Light “. In a vacuum, light normally travels in a straight line. But in a space deformed by a massive celestial body, such as a galaxy, this path deviates! Thus, a light source located behind a galaxy has an apparent position that is different from its real position: this is the phenomenon of gravitational mirage © CEA, Animea

The discovery is published today via an article in the newspaper Nature, where we also learn that Earendel was a star at least 50 times the mass of the Sun, making it one of the most massive known. However, the theory of stellar structure and evolution also tells us that this kind of star can only live for a few million years at most. She definitely exploded in supernova SN II a very long time ago and left behind a compact star which must be a neutron star or a stellar black hole.

For us it is still present and will certainly be studied in more detail in the near future with the telescope. James Webb.

Hubble broke a new record, as this video explains. For a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Select “French”. © NASA’s Goddard Space Flight Center

Earendel, a type III population star?

The data that James-Webb will collect will already be used to clarify the nature and properties of Earendel, because even if the gravitational lensing produced by the galaxy cluster has already allowed us to estimate some of them, such as its temperature, mass and its radius, there is still uncertainty on this subject. In fact, Earendel, for example, could be a double star.

The most interesting perspective would be that we are standing in front of a star formed from gas almost pure from the Big Bang, i.e. a mixture of hydrogen andhelium which would have been almost unchanged by the production of heavier nuclei, carbon andoxygen especially in the very first stars. It is believed that these must have been different and notably more massive than the stars that formed in the galaxies billions of years later. Earendel could thus be similar to these primitive stars, which are said to belong to a type III population because they are very old.

that Sun are part of the stars of the type I population and the stars older than 10 billion years, not very massive and therefore long-lived, found in piles of balls or the star halos of galaxies are part of type II populations.

Astrophysicist Rogier Windhorst tells us about his discovery of Earendel and stellar populations. For a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Select “French”. © ASU School of Earth and Space Exploration

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