. In particular, we expect the JWST to shed some light on what happened shortly after the end of the followed by the “cosmic rebirth”, also called the cosmic, which is the epoch of re-ionization (EoR), when powerful light sources – whose origin is not yet known with certainty – began to significantly re-ionize the neutrals that had formed in a few thousand years, about 380,000 years after the .
Astronomer Michelle Thaller explains to us in this video what the Cosmic Dawn is, a period of re-ionization, which will make it possible to study the James-Webb and not just him. To obtain 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”. Choose “French”. © NASA Goddard Space Flight Center
The precise date of the beginning of the re-ionization is subject to debate, and all that can be said is that it occurred between 100 and 400 million years after the. Before, at the very beginning, no existed yet, but during the EoR there is reason to think that those which formed and shone were very massive, at least 50 to 100 million solar masses. We are talking about these in terms of stars of just like a 3 month old baby is older than a 1 month old baby.
A nearly population III star?
Thestellar tells us that these stars lived a million years at the most, producing by stellar for the first time in the observable nuclei heavier than the which they will then disperse in the young by exploding as a supernova. In doing so, they will modify the composition of the where new stars can be born by gravity, subsequently favoring 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 of 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 theand which 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 by the Michelle Thaller, alas in English in the video above, an example of stars with very little difference in composition and properties, born just after them.
Remember that she was only flushed out with the help of ai.e. the magnification effect (in this case by a factor of at least 1,000) caused by the field of of one intervening between Earendel and Hubble, deflecting light rays like a magnifying glass.
Calculations then indicated 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 posted on.
Hubble breaks all records for the most distant star ever observed
Article ofpublished on 03/04/2022
Thehas just shown that we could always count on him to set a distance record for stars in the distant Universe, before the commissioning of the James-Webb telescope. The has just announced that he had imaged the most distant star known to date, as it was 12.9 billion years ago.
Her name is earphone and one would think that it is a variation of the name ofFor rentone of the elvish characters created by the British writer JRR Tolkien and which is mentioned in The Lord of the Rings. NASA explains, however, that it is an old English term meaning ”“. But, for us, it is above all a star observed when the Universe was only 7% of its age, which means that the which were collected with the Hubble telescope took 12.9 billion years to reach it.
The most distant star known to date
It is in fact the most distant star ever discovered to date and like some of the distant galaxies which, in their time, broke distance records thanks to the Hubble telescope, thetook advantage of of a significant distribution of mass to make an additional zoom that this alone could not do on of the noosphere. In this case, it was the WHL0137-08 cluster of galaxies that broke the previous record for a solitary star. Indeed, Hubble had then managed to look 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 usually travels in a straight line. But in a space deformed by a massive celestial body, like a galaxy, this trajectory is deviated! Thus, a light source located behind a galaxy has an apparent position different from its real position: this is the phenomenon of gravitational mirage. © CEA, Animea
The discovery is published today Going through an article in the newspaper, 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 certainly exploded in SN II a very long time ago, leaving behind a compact star which must be a or one .
For us, it is still present and it will certainly be studied in more detail in the near future with the telescope..
Hubble broke a new record, as this video explains. To obtain 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”. Choose “French”. © NASA Goddard Space Flight Center
Earendel, a type III population star?
The data that the James-Webb will collect will already be used to clarify the nature and properties of Earendel because even if the gravitational lens produced by the galaxy cluster has already enabled us to estimate some of them, such as its temperature, mass and its radius, there are still uncertainties on this subject. In fact, Earendel could be a double star for example.
The most interesting perspective would be that we are in front of a star formed from thealmost pure from the Big Bang, i.e. a mixture of hydrogen and which would hardly have been changed by the production of heavier cores, and oxygen in particular, 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. Thus, Earendel could look a lot like these primitive stars that are said to belong to a type III population, because they are very old.
The Sun is part of the stars of the type I population and the stars older than 10 billion years, not very massive and therefore long-lived, which are found in theor the stellar halos of galaxies are part of type II populations.
Astrophysicist Rogier Windhorst tells us about his discovery of Earendel and star populations. To obtain 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”. Choose “French”. © ASU School of Earth and Space Exploration