Nearly 13 billion light-years is an astonishing distance even for a telescope as sharp-sighted as Hubble. Usually, at such a distance, its optics can only see large galaxies, each of which has millions of stars. And yet NASA’s space observatory managed to discern the ancient star Earendel on the edge of the universe – thanks to a physical phenomenon predicted by the theory of relativity.
When the light from a distant star “shocks” on its way into some massive (by cosmic measure) object – such as a neutron star or a cluster of galaxies – the gravitational field created by this object bends the space around it, changing the orbit of light rays, which i As a result, they walk around, while gaining an extra impulse.
In science, this phenomenon is known as “gravitational lensing” because the massive body here acts as a lens and amplifies the light rays.
Usually, with this method, scientists discover distant galaxies, but in this case, a single star was lucky: its light rays were amplified so much that they hit the telescope.
“We were simply incredibly lucky,” admitted Brian Welch, an astrophysicist from Johns Hopkins University in Maryland, in an interview with the BBC. “If you find the right point, as in our case, the increase is a thousandfold.”
The previous distance record was held by a star named Icarus. Hubble also found it – at a distance of “only” 9 billion light-years from Earth.
Arendel is much further away, and we observe the star at a time when about 900 million years have passed since the Big Bang, and the universe was in its infancy.
By the way, the name of the star Arendel (in fact, it is not officially called that romantic – WHL0137-LS) has nothing to do with the magical kingdom of Arendel from the Disney cartoon Frozen, but comes from the old English word meaning “morning star”. Yes, and in the Hubble image, it’s more likely to be just a weak point.
Another thing is that in the eyes of the astronomers who discovered it, Arendel looks completely different. At the same time, they willingly admit that they still know little about this star. They can not even say with certainty how big it is: it is clear that it is at least 50 times larger than our sun, that is, one of the largest stars discovered so far, but it may turn out that it is actually much larger, times at 500!
It is also possible that Hubble discovered the so-called double star, that is, in fact two stars whose orbits are close together. This is a very common phenomenon, but in this case one of the stars must be significantly more massive than the other, and it is its light signal that will dominate.
However, there is an alternative explanation: Arendel is not actually a distant star, whose light was refracted and amplified, passed by a cluster of galaxies, and an object in the foreground with a star-like light signature, for example, a brown dwarf. However, this is unlikely, as the object remained static for 5 years of observations, while the dwarf, which is much closer, would need to move slightly in space.
One of the most fascinating mysteries is the composition of the new old star. Astronomers have reason to believe that Arendel is one of the primary stars formed by the urgas that arose as a result of the Big Bang.
The theory is that the first stars only consisted of hydrogen and helium, but that caused them to burn out rapidly for a few million years, after which they collapsed. And only after the stars “got hold of” heavy elements did outer space begin to look like we are used to.
But if Arendel really is a primary star, it could only last 900 million years after the Big Bang if it were formed from an isolated, undiluted gas cloud – and this, although possible, is still very unlikely.
“We suspect that Arendel is probably a little enriched by heavy elements, but not to the same extent as the stars that surround us today,” Welch explains. “There is even a small chance that this is the so-called population III star [к гипотетическому населению III принято относить первое после Большого взрыва поколение тяжелых звезд, которые, опять же в теории, не дожили до наших времен]. According to some theories, such stars can still be found on the edge of certain galaxies. “
If astronomers are destined to find such stars, Hubble’s successor, the James Webb Space Telescope, launched last December and armed with much more advanced equipment, will be able to do so.
James Webb will be fully operational in a couple of months and Brian Welch and colleagues have already had time to work on the new space observatory to take a closer look at Arendel.
By the way, no one is going to write about the old Hubble either. Although launched as early as 1990 and somewhat obsolete, this telescope continues to help scientists make great discoveries.
“The Hubble Telescope is doing great,” said NASA employee Dr. Jennifer Weissman. “It is powerful, it has a high scientific performance, and we hope that Hubble will make many more discoveries in the future. And, of course, we are very happy that it will work in parallel with James Webb. With these two telescopes at hand we can learn a lot more about the universe than we have been able to do so far. “