The james webb space telescope continues to prepare his instruments to begin what is expected to be a fruitful and long season of work. However, his predecessor has not stopped giving us good news. And it is thanks to Hubble a team of scientists from John Hopkins University has managed to detect a star that formed 900 million years after the Big Bang. This makes it the most distant ever found, since finding star systems from before 1,000 million years after the big bang was a challenge.
In fact, in the history of the universe there is a gap of immense uncertainty, between 400,000 years and 1,000 million years after the Big Bang. The detection limit of the most precise instruments created by human beings prevented scientists from setting their eyes on that period of history. However, Hubble is not just any instrument.
Thanks to him it had already been detected previously a galaxy formed 250 million years after the Big Bang. But nothing similar had been achieved with a star or star system. At least it had not been done until now, since it has been Hubble itself that has once again achieved it. The research data is published today in Nature.
The dark age after the Big Bang
radiation from microwave background It is a type of electromagnetic radiation that occupies the entire universe. Thanks to their study, it is known with some precision what the universe was like 400,000 years after the Big Bang.
At that time the temperature was low enough for protons and electrons to join together to give neutral hydrogen. In this way, part of the seed was sown that would eventually give rise to the stars. However, it was still early.
The problem is that from that moment there is a long period in which it is not known how everything evolved. The following data that had been obtained until recently were from 1 billion years after the Big Bang. By this time there were already small galaxies, gamma-ray bursts, and even bright quasars probably powered by supermassive black holes as heavy as a billion suns. Little by little, all kinds of objects that have emerged since then have been detected. But first it was all doubt.
According to the physicist Tom Abel in an article for PhysicsTodaythis period is known in cosmology as the Dark Age and contains many questions. For example, which formed first, black holes or galaxies? The most massive stars or the low mass ones? Could some of those early stars still exist today? They are all unknowns that could only be resolved by an instrument as powerful as the hubble space telescope.
It was this one that found that galaxy formed 250 million years after the Big Bang, the MACS1149-JD1. And he has now been the one who has found the first known star of the dark period of the universe. Thanks to him we have a lot of data about this star, which they have baptized as Earendel, which means “morning star” in Old English. There are still some unknowns. However, it is hoped that James Webb will be ready and that, as a worthy successor, he can provide the information that we lack. But what do we know so far about this star?
Another great Hubble find
Hubble was able to detect this star thanks to an effect known as gravitational lens. This occurs when light from very distant objects bends when it meets a very massive object located between its source and the observer.
Observing this effect, models can be made about the origin of that light. In this case, according to the study that has just been published in Natureall the models pointed out that its radius was less than that of any star cluster. Therefore, they were not before a set of stars, but before a or at most a binary star system.
They have also been able to calculate that its mass is possibly greater than 50 times that of the Sun and that it has a red shift of 6.2. This term refers to a phenomenon that occurs when the electromagnetic radiation that is emitted or reflected from an object, usually visible light, appears shifted towards red, located at the end of the electromagnetic spectrum. It is data that can be used to calculate how distant an astronomical object is. The higher the number, the further away it will be. Or, what is the same, the oldest will be its origin in the history of the universe.
Previous observations of stars detected and magnified by gravitational lensing have yielded redshift values of between 1 and 1.5. This is much larger, as it is the most distant single star ever detected. So much so that it was formed 900 million years after the Big Bang.
With the Models made from the hubble data These scientists have also concluded that it was most likely at a temperature of 20,000K However, they have not been able to accurately determine its spectral type. But there are still ways to find out. And it is that, when it is ready, the space telescope james webb It could give this data and, in addition, report more accurately than Hubble on its mass and temperature.
The veteran and the rookie will work together to shed some light on the darkest period in the history of the universe.