The history of our universe revealed by the James Webb telescope

The James Webb telescope – the most powerful (and expensive) space instrument ever built – has set out to discover the most secretive parts of the universe and revealed its first images on Tuesday July 12 . And the beauty of the spectacle was certainly worth the years of waiting.

Launched in December, this little technological gem is now 1.5 million kilometers from Earth. Thanks to his huge primary mirror of 6.5 meters and his instruments that detect infrared signals, James Webb is able to see not only the very old universe as it existed shortly after his birth more than 13 billion years ago, even through clouds of dust but also to study exoplanets by detecting molecular signatures of methane, ammonia and other organic compounds that may be present in their atmosphere. All of this much faster than previous telescopes like Hubble were able to do.

The first images revealed were selected by an international committee made up of representatives from NASA, the European Space Agency (ESA), the Canadian Space Agency and the Space Telescope Science Institute.

Also read: Successful start for the James Webb telescope, a mirror of origin

SMACS 0723

SMACS 0723 is the first-ever image revealed by the James Webb Space Telescope on Tuesday evening. It shows the galaxy cluster SMACS 0723 as it looked 4.6 billion years ago. “This is the deepest and clearest infrared image of the distant Universe ever taken,” according to NASA. The latter was recorded in an observation time of 12.5 hours and one can observe thousands of galaxies that vary in shape or color. Some are orange, others white. Most stars are blue, and sometimes as large as the more distant galaxies that appear next to them.

A very bright star can be seen to the left of center. Between its peaks between 4 and 6 o’clock are several very bright galaxies that are part of the SMAC 0723 cluster. If some galaxies appear curved, it is because the combined mass of the galaxy clusters in the foreground act as ‘gravitational lenses’, bending the light rays from galaxies farther behind, making them larger.

This part of the universe covers a section of the sky about the size of a grain of sand held at arm’s length by a person on the ground.

The Carina Nebula

The Carina Nebula, also called NGC 3372, was discovered in 1752 by the French astronomer Nicolas-Louis de Lacaille at the Cape of Good Hope in South Africa. One of the largest (spanning just over 300 light-years) and brightest nebulae in the sky, it is located about 7600 light-years away in the southern constellation of Carina.

What appear to be jagged mountains on a moonlit evening are actually the rim of a young star-forming region, NGC3324, in the Carina Nebula dubbed the “cosmic cliffs.” The cavernous area was carved into the nebula by intense ultraviolet radiation and stellar winds from extremely massive and hot young stars. The high-energy radiation from these stars shapes the nebula’s wall by slowly eroding it.

Nebulae are stellar nurseries where stars form. The Carina Nebula is home to at least a dozen bright stars whose masses are estimated to be 50 to 100 times that of our Sun.

The Southern Ring Nebula

The Southern Ring Nebula, also known as the “Eight Shards” Nebula or NGC 3132, is a planetary nebula, an expanding cloud of gas surrounding a dying star. Its size is estimated to be almost half a light-year across and it is located about 2000 light-years from Earth. It is one of the closest known planetary nebulae.

The name “planetary nebula” refers only to the round shape that many of these objects exhibit when examined in a small telescope. In reality, as NASA reminds us, “these nebulae have nothing to do with planets, but rather are giant envelopes of gas ejected by stars at the end of their lives.” These gases travel at a speed of 10 km per second.

“What we are seeing is the grand spectacle of a star’s end of life,” analyzes Pierre Ferruit, scientific director of the European Space Agency’s contribution to the James Webb Space Telescope. At the end of its life, a star pulsates, and with each pulsation it loses part of its matter. What we see in the center is a white dwarf, a very small and very hot star that is emitting very energetic radiation. The blue color represents the areas excited by the energetic radiation and the red represents the gas expelled from the central star.

WASP-96b

WASP-96b is a giant planet outside of our solar system, located nearly 1150 light-years from Earth in the constellation of the Phoenix, whose discovery dates back to 2014. Composed mostly of gas, it orbits its star every 3.4 days.

James Webb did not take a direct image of the planet or its atmosphere, this is an indirect image of the spectrum of the exoplanet passing in front of its star. Still, it underscores the presence of water vapor in the atmosphere of WASP-96b.

WASP-96b is about 20% larger than Jupiter but half the mass, closer to that of Saturn. However, because the latter is much closer to its parent star than Saturn is to the Sun, its temperature is oppressive, putting it in the “hot Saturn” category.

In 2018, by examining the composition of WASP-96b, a research team from the University of Exeter (UK) had shown that the latter is composed of sodium and that its atmosphere is clear and cloudless. However, data from the James Webb Space Telescope have revealed details of this exoplanet’s atmosphere that are still hidden: the clear signature of water, evidence of haze and evidence of the existence of clouds, which we therefore assumed to be non-existent based on previous observations.

Also read: Capturing an Exoplanet User’s Guide

Stephen’s Quintet

Stephan’s quintet lies about 290 million light-years away in the constellation Pegasus. It is the first group of compact galaxies ever discovered and is located about 340 million light-years from the Milky Way.

The Stephan Quintet was first observed in 1878 by French astronomer Edouard Stephan from the Marseille Observatory. It was then cataloged as a collection of nebulae when in reality they are galaxies made up of billions of stars. Only four of the five galaxies are in the same region of space and show signs of gravitational interaction. We see gas filaments and stars escaping from it, evidence of the gravitational pull at work.

“The galaxies we see on the right are close enough to interact,” explains Pierre Ferruit. It’s a kind of cosmic dance where the galaxies interact.” Two eyes and a smile seem to appear at the bottom right, “these are the nuclei of two merging galaxies,” explains the latter.

Meanwhile, the tallest galaxy in Stephan’s quintet – NGC 7319 – is home to a supermassive black hole with a mass of 24 million times that of the Sun. It actively traps and agglomerates matter under the influence of gravity and emits light energy equivalent to 40 billion suns.

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