The secrets of the emergence of stars and galaxies.. a huge telescope is preparing to discover them

After its launch, the James Webb Space Telescope will unveil more secrets of the beginnings of the cosmic dawn, when the universe's first stars and galaxies arose.

James Webb assumes the task currently entrusted to the Hubble telescope, which is to observe space in the visible light field in particular, but it is distinguished by probing the depths of a wavelength that is not within the reach of the eye, which is the middle infrared.

The farther a distance is visible in space science, the more ancient time distances are provided.

While it takes eight minutes for the particles of sunlight to reach the eye on the planet, the “James Webb” dome seeks to capture the light of the first galaxies dating back more than 13.4 billion years, those that appeared in the modern universe less than 400 million years ago. the great explosion".

But as it expands, this light travels a longer distance to reach the beholder, at which point it becomes red.

Like the sound of an object that when it moves away weakens, the light wave expands and travels from the frequency that the naked eye can see, to the infrared.

The Hubble telescope, which was launched in 1990, reached a limit of 13.4 billion years with the discovery of the "GN-z11" galaxy, which is a small unimportant spot, but it "formed a surprise because its brightness was not expected within this distance," according to what "Mcnashveha" explains. Astrophysicist Pascal Auch told AFP.

Osh expects that the James Webb telescope will provide images "more accurate thanks to a capture capacity 100 times greater, which will allow the discovery of this era in detail", as well as the discovery of many galaxies, but much less bright.

The beginnings of the stars

Thanks to his infrared ability, James Webb will not only be able to observe ancient phenomena, but also interstellar dust clouds that absorb light from stars and block it from Hubble.

"This invisible light allows us to see what is hidden among the clouds, that is, the emergence of stars and galaxies," explains David Elbaz, astrophysicist at the Atomic Energy Authority.

He adds: "The French Atomic Energy Authority is running the project of the imaging device "MERIM", which, together with the MRS spectrometer of the US space agency "NASA", will study these structures in the mid-infrared, and will also be able to "see the fingerprint of atoms in distant galaxies." .

The great importance of this is that it allows the interpretation of a major stage in the evolution of the universe, which is the stage in which "the light was released, that is, when the first stars began to form", or what is known as the "cosmic dawn".

And the universe entered a short period after the "Big Bang" in a "dark age", in a neutral gas bath consisting mainly of hydrogen and helium, without light.

The theory indicates that this gas condensed into "wells" of mysterious and undetectable black matter, in which the first stars arose.

These stars multiplied like a snowball, and began to electrically charge the neutral gas of the universe, which is called ionization.

A process called "reionization" pulled the universe out of its obscurity and made it "transparent".

"It is not known, however, when the first galaxies formed," explains astrophysicist Françoise Combe.

Simulations suggest that this happened during a period that extended between 100 and 200 million years after the "Big Bang".

And she adds, "The theory is that all the small galaxies will re-ionize the universe because their number is very large, and what we will be sure of with 'James Webb', is whether their number is sufficient for that."

But no one thinks that seeing the first stars will be possible.

These giant stars, called "Peoples 3", consisting of a hundred to a thousand solar masses with a tremendous temperature and a short life, will begin to ionize the neutral gas of the universe.

Studying this phenomenon is tantamount to studying the formation of galaxies.

Nicole Nesvadba, an astronomer at the Lagrange Laboratory of the Côte d'Azur Observatory, believes that the hope is "to see the first galaxies that carry the second generation of stars, which may provide a lot of data about the first stars."

"I don't know, ask us in five years," she jokes.

The launch of the James Webb telescope has been postponed three times, most recently on Tuesday.

And NASA announced that the reason for the delay was “bad weather” in the city of Koro, noting that “the new launch date is December 25.”

The first delay in launching the telescope was linked to an accident that occurred during its preparations at the end of November, while the second delay was due to a connection problem with the Earth system.

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