50 times the size of the Sun, we see it thanks to a cluster of galaxies that acts as a magnifying glass. Due to the expansion of the Universe, it is now 28 billion light years away from us
Earendel in Old English means “morning star” or “rising light”. It is the name given to the oldest and most distant single star ever discovered so far. Earendel’s light was emitted 12.9 billion years ago but now, due to the expansion of the Universe, it would be 28 billion light years from us (it would “be” because in reality it is very likely that there be more, exploded as a supernova long ago). Its light was captured by the Hubble Space Telescope and studied by a research team led by Brian Welch of Johns Hopkins University in Baltimore, whose work has been published in Nature
.
Age
Earendel’s age was calculated on the basis of the very high red shift of its light (equal to 6.2), a value that indicates the speed of the star’s departure from us, but from which the elapsed time can also be derived. from when the light was emitted until today. Considering the enormous distance, Earendel could only be observed thanks to an effect hypothesized by Einstein: the distortion of time-space due to a body of great mass that is interposed between us and the object to be observed and which in practice acts as a a magnifying glass. This is the case of the galaxy cluster WHL0137–08 which deflected and concentrated Earendel’s light allowing the Hubble telescope to notice it.
After the Big Bang
The star therefore formed “only” 900 million years after the Big Bang, the initial impulse that started our Universe. Is it possible to see even older stars? With the new James Webb space telescope, which is about to go into operation after the launch last December, it will be possible to see even more ancient and distant stars, but up to a certain point. The galaxy GN-Z11 has already been seen thanks to Hubble at 13.4 billion light years away, but in any case it will never be possible to see the light beyond the limit of 300 thousand years after the Big Bang (which occurred 13, 8 billion years ago).
Deep inside
It is not possible because before 300,000 years after the Big Bang, light could not travel: the Universe was so dense and hot, full of electrically charged protons and electrons and very close to each other, that light particles (photons) they were continually being diverted and could not proceed. In practice, beyond that limit it is as if there was a thick fog that prevents the light from coming out and therefore does not allow us to see beyond. Only when 300,000 years had passed since the Big Bang, in what scientists call the ‘surface of last scattering’, did the temperature of the Universe drop to a level where protons and electrons could unite to form the first atoms and photons therefore found free field to be able to travel undisturbed to us. We can still “see” them: it is the cosmic microwave background radiation, identified for the first time in 1965, which permeates the entire Universe in a uniform way, apart from some infinitesimal (but very important) differences on a cosmic scale. However, thanks to gravitational waves, also hypothesized by Einstein but identified only in 2016, it will be possible to discover something more about the most ancient phases of the Universe.
April 5, 2022 (change April 5, 2022 | 20:20)
© Time.News