The Hubble telescope has discovered the most distant star ever observed. This distant space object is about 12.9 billion light-years from Earth. The light from this star was emitted shortly after the Big Bang, was multiply amplified by foreground galaxies, and was stretched by the expansion of the universe.
The star was named Earendel, which, in Old English, means "morning star" or "rising light. And the name is justified for the star we see as it was just 900 million years after the beginning of the Universe. It is the most distant star ever observed (the previous record holder, a blue supergiant named Icarus, is about 4 billion light-years closer).
However, these numbers can be a bit confusing. Earendel's distance of 12.9 billion light-years and Icarus' distance of 9 billion is what's called "hindsight time," where the current day is used as a point of reference. So it took Earendel's light 12.9 billion years to reach us here on Earth, but now the star is much farther away because of the expansion of the universe.
In fact, the rate of that expansion is one of the tools used to measure such incredible distances. As light passes through space, the expanding universe stretches its waves, shifting them toward the red end of the spectrum. Calculating this red shift determines how far away the source is-the greater the red shift, the farther the distance. In this case, the Earendel redshift was 6.2 units, much larger than the redshift of Icarus, which is only 1.5 units.
Although some galaxies and stellar clusters have been observed at even greater distances, individual stars are much harder to detect under these conditions. To the astronomers' aid came a closer galaxy, which, through its enormous gravity, bends space-time itself. Through a phenomenon known as gravitational lensing, this galaxy bent the light from Earendel and amplified it, making it visible to Hubble.
Given the lensing effect, astronomers were able to determine that Earendel has more than 50 times the mass of the Sun. There is a possibility that it is not one single star, but a multiple system of two or more stars, but this does not detract in any way from the results of its discovery from such a great distance.
Astronomers have not yet been able to measure other properties of Earendel, such as its temperature, spectrum and stellar structure, but those details may be available from the James Webb Space Telescope, which should begin observations in a few months.
The study was published in the journal Nature.
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