The Hubble Telescope has photographed a star 12.9 billion light-years away from us. It is the most distant star ever discovered.
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The Hubble Telescope (Hubble) continues to break new records. This week, a study was published in Nature which reports the most distant star we have so far managed to photograph. The star is called WHL0137-LS but has also been given the simpler name Earendel which means morning star.
– We almost did not believe in it at first. It is so much further away than the previously most distant and red-shifted star, says Brian Welch, an astronomer at Johns Hopkins University in Baltimore and lead author of the study, in a press release published by Nasa.
Gravity lenses made the observation possible
Earendel has long since ceased to exist, but due to the enormous distance to the star, it can still be seen from Earth. The star is believed to have been around fifty times larger than the sun and several million times as bright.
The star breaks the previous record for the most distant star and is estimated to be 12.9 billion light-years from us. The former record holder, the star Icarusis a blue supergiant located 9 billion light-years from Earth.
Stars at these extreme distances can usually not be observed as the light reaching us is not enough. But due to what are called gravitational lenses, the light from distant objects can be bent, which, if we are lucky, allows us to see them. Gravitational lenses were predicted by the general theory of relativity and function as natural telescopes.
In this case, the gravitational lens is the galaxy cluster WHL0137-08 which lies between the earth and Earendel. The mass of the heap is so large that it bends light and acts as a magnifying glass. The star is located in the galaxy Sunrise Arc, which is distorted by the gravitational lens and appears as a long elongated arc.
Earendel’s position behind the cluster means that the star’s light is amplified a thousandfold and clearly stands out compared to the rest of the galaxy.
An illustration of how a gravity lens works. Photo: Science Photo Library / TT
The star is old, but not the oldest
That Earendel is 12.9 light-years away means that the light we see today was emitted from the star when the universe was only around 900 million years young.
– Earendel existed so long ago that it has not necessarily had the same raw material as stars that are around us today. Studying Earendel will provide insight into an age of the universe that we are unfamiliar with, but which has led to everything we know now. It’s like we read a very interesting book – but started with the second chapter. Now we have a chance to find out how it all started, Brian Welch said in the press release.
However, Earendel is not the oldest star we have observed, although it is the most distant. The star HD 140283 has an estimated age of 13,7 billion years and is therefore believed to have formed shortly after the birth of the universe. The star has been nicknamed Methuselah after the biblical patriarch who became 969 years old. However, there are studies that claim that Methuselah is only 12 billion years old.
Earendel will be examined in more detail by Webb
In addition to being the most distant star, Earendel is also the most red-shifted we have observed. The fact that a light from a star is red-shifted means that the wavelengths go towards the infrared part of the electromagnetic spectrum. This happens when the universe expands and the light from distant objects, such as stars, is stretched.
The Hubble Telescope on the left and an illustration of the Web Telescope on the right. Photo: NASA / AP / TT
Hubble is equipped to measure ultraviolet, visible and near infrared light. The recently launched James Webb Telescope (Webb), on the other hand, is designed to look at the universe with much higher accuracy through the infrared part of the electromagnetic spectrum.
This means that Webb will be able to look further into the universe than Hubble can.
– We expect to be able to confirm that Earendel is actually a star with the help of Webb, and to measure its brightness and temperature. We also expect to see that the Sunrise Arc galaxy lacks heavy elements that form subsequent generations of stars. This would indicate that Earendel is an unusual, massive and metal-poor star, says Dan Coe, co-author of the study in the press release.
Recently, the first sharp image was taken with Webb after its segmented mirror was clearly calibrated.
The discovery of the star Earendel is a perfect structure for the first research results from Webb that are expected to come during the summer.
– With Webb, we could see even more distant stars than Earendel, which would be incredibly exciting. We will look as far back as we can. would like to see Webb beat Earendel’s distance record, says Brian Welch in the press release.
Namnet Earendel
Earendel (in Swedish Aurvandil) is a figure that is included in Nordic mythology. He freezes his toe as he is carried across a river by the thunder god Thor. Thor then takes Aurvandil’s toe and throws it up in the firmament where it forms a star.
Earendel has also given a name to JRR Tolkien’s character Eärendil which can be found in the book Silmarillion.
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