HUBBLE TELESCOPE OBSERVES THE FARTHEST STAR IN THE UNIVERSE!
On Wednesday,
March 30, 2022, NASA publicly announced one of the most amazing discoveries in recent years,
the Hubble Space Telescope managed to observe the farthest star ever seen, a light source that
emerged just 1 billion years after the Big Bang. "Introduction"
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This great discovery was achieved thanks to one of the most powerful
telescopes there is and a small stroke of luck.
The star discovered by Hubble was nicknamed Ärendel by astronomers
and according to measurements emitted its light in the first billion years of the universe. This
is a significant jump compared to Hubble's previous distance record, in 2018,
when it detected a star with an estimated age of 4 billion years after the Big Bang.
The Hubble telescope received a help from the universe, by looking through space
deformed by the mass of the huge galaxy cluster WHL0137-08, this cumulus caused an
effect called gravitational lensing around it. Thanks to this, it was possible to see the star
Earendel which was aligned very close to a wave in the fabric of space created by
the mass of the cluster, which increases its light enough to be detected by Hubble.
For now there is not much information about the star, only its distance and brightness are known,
but it is expected that as soon as it begins its operations, NASA's James Webb telescope
will follow up to know the temperature and composition of Eärendel.
For now astronomers remain conservative and the possibility that Earendel is one
of the stars of the first generation of the universe is not contemplated,
however, we are all very eager to know more information about this star and its environment,
since that would show us the conditions that the environment of the early universe had.
HOW FAR IS THE STAR DISCOVERED BY HUBBLE? The newly detected star is so far away that
its light has taken about 12.9 billion years to reach Earth, and it appears to
us as when the universe was only 7 percent of its current age, with a redshift of 6.2.
The smallest objects previously seen at such a great distance are star clusters,
embedded within the first galaxies, never before has it been possible to
observe an individual object as small as a star at such a distant distance.
Astronomer Brian Welch of Johns Hopkins University in Baltimore,
lead author of the paper describing the discovery, mentions that the discovery was made from data
collected during Hubble's RELICS (Reionization Lensing Cluster Survey) program,
led by co-author Dan Coe at the Space Telescope Science Institute (STScI). Also in Baltimore.
REDSHIFT In astronomy,
redshift is the effect that occurs when a distant astronomical object such as a star or galaxy
is far away and its visible light spectrum shifts toward the redder light stripes.
Why does this happen? The redshift is due to the expansion of the universe,
because the space between the galaxies expands and they move away every second and the light waves
that travel through the universe are stretching and losing energy, because of this the colors of
the galaxies are running towards the frequencies of weaker visible light, that is, the red ones.
The farther away a galaxy or star is, its redshift will be greater because
the light must travel a greater distance and therefore travel for much longer.
The star discovered by Hubble is located at a distance of almost 13,000 million light years,
this makes it the farthest individual object that has ever been seen,
however, we did not get an image of this star because it is very bright.
Normally, at these distances, an entire galaxy looks like a small
blob, with the light of millions of stars mixed into a single point, but if such a distant galaxy
is already very difficult to see, how did we see a single star so far away from our galaxy?
The reason is that the light of this star passed through a gravitational lens
formed by a gigantic galactic cumulus which magnified its light more than a thousand times and
in this way we could observe it as an individual object augmented by a natural magnifying glass
called gravitational lensing, but... WHAT ARE GRAVITATIONAL LENSING?
In astrophysics, a gravitational lens, also called a gravitational lens, is formed when
light from distant, bright objects such as quasars curves around a massive object (such as a galaxy)
located between the sending object and the receiver.
Gravitational lensing was predicted by Einstein's theory of general relativity. In
1919 it was possible to test the accuracy of the prediction during a solar eclipse,
the astronomer Arthur Eddington observed how the trajectory of light from distant stars was curved
as it passed near the Sun, producing an apparent displacement of their positions.
A gravitational lens can be considered as a deformation of spacetime
caused by the presence of massive objects and the higher the concentration of these bodies,
the greater the gravitational lensing. Gravitational lensing can be used as
in a huge magnifying glass that magnifies hundreds or even thousands of times the light
coming from very distant objects. This is how the star Eärendel was detected.
In addition, gravitational lensing can be used in the completely opposite direction:
that is, from the deformation of the background sources the mass
distribution of the object that acts as a lens can be deduced.
This is especially useful in the case of galaxy clusters
and has the advantage that it is also able to track the dark matter of a galactic cumulus.
Unfortunately gravitational lensing is not something we can control,
we don't decide where there's going to be a gravitational lens, we just find them and hope
that with some luck something is right behind them so we can observe it with our powerful telescopes.
OBSERVATION BY CHANCE Although it might seem
like something planned the reality is that the observation of the star Eärendel was pure chance,
the main objective of the Hubble telescope was to study the cluster of galaxies WHL0137-08, however,
the mass of the galaxy cluster drastically deformed the fabric of space, creating a powerful
natural magnifying glass that greatly distorts and amplifies the light of the objects behind it.
Thanks to this fortunate alignment with the crescent galaxy cluster, the star Eärendel
appears in front of the cumulus directly or very close to a wave in the fabric of space.
This ripple, which is defined in optics as "caustic", provides maximum magnification
and brightness. This caustic causes the star Eärendel to protrude from the general
glow of its home galaxy. Its brightness is magnified a thousand times or perhaps more.
THE JAMES WEBB WILL FINISH THE JOB For now, astronomers who have studied
the discovery cannot determine whether Eärendel is a binary star, although most massive stars
have at least one smaller companion star. According to the first analyses Eärendel existed
so long ago that it may not have had all the same raw materials as the stars around us today,
because of this Eärendel will be a window into an era of knowledge about the early universe.
The Hubble telescope has observed everything that its lenses allow it,
but it can no longer do more, with the technology it has it is not able to analyze the star in mid-
or far-infrared frequencies, for that we will have to wait for the James Webb to come into operation.
Astronomers expect Eärendel to be visible in the years to
come. Thanks to this we will have enough time to observe it with NASA's James Webb Space Telescope
since we need the james Webb's high sensitivity to infrared light to learn more about Eärendel,
because its light stretches to longer infrared wavelengths due to the expansion of the universe.
The James Webb Space Telescope is expected to measure the star's brightness and
temperature. These details will reduce its type and stage in the stellar life cycle. It
is also expected to discover what materials the Sunrise Arc galaxy
that contains the star Eärendel possesses. If Sunrise Arc galaxy contains heavy elements
that form in later generations of stars. This would mean that Earendel is a rare, massive,
metal-poor star, one of the stars of the second or third generation of the universe.
Eärendel's composition is of great interest to astronomers, as it was formed before the universe
was filled with the heavy elements produced by successive generations of massive stars.
If follow-up studies find that Eärendel is only composed of primordial hydrogen and helium,
it would be the first evidence of the legendary population III stars, which according
to the most accepted theories by cosmology would be the first stars born after the Big Bang.
While the probability is small, scientists admit that it's a tempting idea anyway,
as it would prove one of the most important hypotheses in modern cosmology.
For now the Hubble telescope has already done its job, now it's up to the James
Webb telescope to give us the information it needs to uncover more mysteries about that star
and the early universe it was in. A NEW ERA OF DISCOVERY
With the discovery of the star Eärendel opens up endless possibilities, for now it only remains
to wait for the James Webb telescope to come into operation with which according to the astronomers
who made the discovery, it is possible that we will be able to break more distance records.
Some records that the James Webb telescope is expected to break are:
- The oldest galaxy in the universe - The first stars in the universe
- The first star clusters The star Eärendel is in the Sunrise
Arc galaxy, according to the first observations this galaxy does not belong to the first galaxies
that formed in the universe, but the James Webb telescope has yet to confirm this, we may be
in the presence of one of the first galaxies in the universe and we still do not know it.
If Sunrise Arc turns out to be one of the first galaxies in the known universe
we could be in the presence of one of the most important discoveries in history, it means that
we are observing the universe just when it was just forming, 1 billion years after the Big Bang.
Although in years of human life 1 billion years may seem like an eternity,
in the universe it only represents 7% of the total age of the entire universe,
which is why looking at this type of object is so important for astronomy.
To look into the distance is to look at the past, the farther away we are able to observe the
universe the more to the past we look, we are able to see events that occurred billions of years ago,
only with the power of science and our most advanced technology.
For now, gravitational lensing is the best tool we have to observe the distant universe, if with the
James Webb telescope we can look even farther than Hubble can look, we could point to the mirrors
of the Webb and look at those corners where Hubble has already observed before and maybe we will find
things that we had not been able to see before. We may find galaxies far away or the first
star clusters that began to form shortly after the universe was born.
The possibilities that open up thanks to this discovery are very great and
the discoveries that are approaching in a few years will be even more amazing than this one.