Talha Mansoor describes an extraordinary phenomenon
The scintillating news of discovering the most distant star ever observed was broken after it was seen through the help of the Hubble Space Telescope which utilized a recently developed observational phenomenon called gravitational lensing. An international team of astronomers detected the blue supergiant star whose presence is described during the period when the universe was just one-third of its current age.
In this context, it was mentioned that this was the first time that scientists were seeing a magnified, individual star. Though astrophysicists can see individual galaxies out there this star is at least 100 times farther away than the next individual that can be studied except for supernova explosions. This is quite unusual and is rated as a singular breakthrough that will go a long way in determining many new facets of the universe as a whole that have eluded astrophysicists up to now. The discovery of this star is rated as unique among astrophysicists dealing with the formation and evolution of stars in the early universe but also the composition of galaxy clusters and even the very nature of dark matter itself. This is clearly out of the ordinary.
It is observed that the newly-discovered star dubbed Icarus by the discoverers started emitting light 4.4 billion years after the Big Bang. Though the star is considered to be very bright in appearance but being at an enormous distance it proved very difficult to be seen by very powerful observatory instruments. But it became visible only due to the process of gravitational lensing.
Gravitational lensing is defined as an effect predicted by Einstein’s general theory of relativity. It takes place when diverging light rays from a distant object are bent back inward as they pass by an extremely massive object such as a galaxy cluster.
When a galaxy cluster moves directly between Earth and a distant background object, gravitational lensing can magnify the distant object by up to a factor of about 50. This technique is very helpful in discovering objects that were hitherto unseen by telescopic procedures.
The discovery came about when Hubble was in the process of detecting and tracking down a supernova named Refsdal whose light was predicted to be gravitationally lensed soon by the galaxy cluster MACS J1149 located some 5 billion light-years away. While going through their observation regime the astrophysicists were surprised to locate another point source that was unexpectedly growing brighter within the same field in which Refsdal was present. While the astrophysicists were waiting for the Refsdal to pass through the predicted lensing process they accidentally stumbled upon the new star.
The first impulse of the discoverers was to measure the spectrum of the star by using Hubble. They broke down the light of the new discovery into its constituent colors and they found out that while the star was getting brighter in the process but it was not getting hotter. This discovery implied that Icarus was not a supernova but a distinct non-exploding star very far off in the distance. They also discovered that the star was not only lensed by the intervening galaxy cluster but also micro-lensed by another small yet massive object within the cluster.
Galaxy Clusters As Massive And Sprawling Structure
It is mentioned that scientists know that the micro-lensing was caused either by a star, a neutron star, or a stellar-mass black hole. The details point out the possibility of further exploring new insights about the makeup of the galaxy cluster itself. Galaxy clusters are rated as the unusually massive and sprawling structures in the universe and going into their details will increase understanding of the cosmos.
There is no doubt that the discovery of a new star may shed fresh light on the most enigmatic scientific riddle known as dark matter. If dark matter is at least partially made up of comparatively low-mass black holes, as it was recently proposed, the astrophysicists should be able to see this in the light curve of Icarus. Their observations do not favor the possibility that a high fraction of dark matter is made of these primordial black holes with about 30 times the mass of the Sun. The successful discovery of Icarus has opened vistas of further breakthroughs about the very evasive building block of the universe.
The astrophysicists are extremely fascinated by this discovery but they are also hopeful that this discovery will surely not be the last one. The gradual development of most modern telescopes such as the James Webb Space Telescope will surely enable astrophysicists to delve deep into the recesses of the universe to explore stars that came into existence during the early formation of the universe. The next step will surely be to find out the earliest possible condition of the universe itself. The Weekender