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Science Notebook

James Webb Space Telescope offers a window into the cosmos

Print edition : Aug 04, 2022 T+T-

James Webb Space Telescope offers a window into the cosmos

A composite image showing what the James Webb Space Telescope looks like deployed in space.

A composite image showing what the James Webb Space Telescope looks like deployed in space. | Photo Credit: NASA, ESA, CSA & Space Telescope Science Institute (STScI)

Each of the first images released contain previously unseen objects.

On July 12, NASA revealed the first spectacular images of the cosmos captured by the James Webb Space Telescope (JWST), the biggest optical space telescope to be built. It was launched on December 25, 2021, aboard an Ariane 5 rocket from Kourou, French Guiana, and in January 2022, it arrived at its home in space, L2 (the closest among the five so-called Lagrange points where the gravitational pull of the sun and the earth precisely equals the centripetal force required for the telescope to move with them).

The JWST’s first Deep Field image. Released on July 11, this is the farthest and sharpest infrared image of the distant universe so far. It is a view of the galaxy cluster in the Southern Sky called SMACS0723, which is about five billion light years away. As NASA stated, this image is approximately the size of a grain of sand held at arm’s length.

Because of its immense size, the cluster is magnifying and distorting background galaxies through an effect called gravitational lensing. Some of these lensed galaxies are the youngest galaxies in the field, being seen at a time more than 13 billion years ago, a billion years after the Big Bang. Webb scientists extracted the spectra of one of the earliest galaxies, and it showed traces of hydrogen, oxygen, and neon atoms. 
The JWST’s first Deep Field image. Released on July 11, this is the farthest and sharpest infrared image of the distant universe so far. It is a view of the galaxy cluster in the Southern Sky called SMACS0723, which is about five billion light years away. As NASA stated, this image is approximately the size of a grain of sand held at arm’s length. Because of its immense size, the cluster is magnifying and distorting background galaxies through an effect called gravitational lensing. Some of these lensed galaxies are the youngest galaxies in the field, being seen at a time more than 13 billion years ago, a billion years after the Big Bang. Webb scientists extracted the spectra of one of the earliest galaxies, and it showed traces of hydrogen, oxygen, and neon atoms.  | Photo Credit: NASA, ESA, CSA & Space Telescope Science Institute (STScI)

NASA developed the JWST in collaboration with the European and Canadian space agencies. It is designed primarily to conduct astronomy in the infrared. Its primary mirror comprises 18 hexagonal mirror segments made of gold-plated beryllium, which effectively provide a mirror with a diameter of 6.5 metres. The JWST has a light-collecting area of about 25 sq. m, about six times that of Hubble, its predecessor. Its high infrared resolution and sensitivity allow it to image objects too old, distant, or faint to be viewed by Hubble. The JWST will enable observation of the first stars and the formation of the first galaxies and a detailed atmospheric characterisation of potentially habitable exoplanets. Each of the first images released contain previously unseen objects ranging from a dying star spewing gas to a quintet of dancing galaxies.

Cosmic cliffs in the Carina Nebula. The “cosmic cliffs” image, which looks like a 3D image of mountains, is testimony to the telescope’s ability to peer through intervening cosmic dust and gas to reveal stellar nurseries and individual stars. The cosmic landscape of mountains—some are as high as seven light years—and valleys seen in this image is a snapshot of the edge of a nearby stellar nursery called NGC3324 at the north-west corner of the Carina Nebula, located in the Milky Way about 7,600 light years from the earth. The “mountains” are studded with glittering young stars imaged in infrared.
The nebula is believed to contain a seemingly endless supply of gas and dust from which new stars and planets are born. “Today, for the first time, we’re seeing brand new stars that were previously completely hidden from our view,” said Amber Straughn, JWST’s Deputy Project Scientist. 
A cavernous region appears carved from the nebula. This is due to the intense ultraviolet radiation and stellar winds from extremely massive, hot, young stars located in the centre of the bubble above the area shown in this image. The “steam” that appears to rise from the “mountains” is actually hot, ionised gas and hot dust streaming away from the nebula because of the relentless radiation. Protostellar jets shoot out from some of these young stars. 
The youngest sources appear as red dots in the dark, dusty region of the cloud. Young stars and their dusty, planet-forming disks shine brightly in the mid-infrared, appearing pink and red.  
Cosmic cliffs in the Carina Nebula. The “cosmic cliffs” image, which looks like a 3D image of mountains, is testimony to the telescope’s ability to peer through intervening cosmic dust and gas to reveal stellar nurseries and individual stars. The cosmic landscape of mountains—some are as high as seven light years—and valleys seen in this image is a snapshot of the edge of a nearby stellar nursery called NGC3324 at the north-west corner of the Carina Nebula, located in the Milky Way about 7,600 light years from the earth. The “mountains” are studded with glittering young stars imaged in infrared. The nebula is believed to contain a seemingly endless supply of gas and dust from which new stars and planets are born. “Today, for the first time, we’re seeing brand new stars that were previously completely hidden from our view,” said Amber Straughn, JWST’s Deputy Project Scientist.  A cavernous region appears carved from the nebula. This is due to the intense ultraviolet radiation and stellar winds from extremely massive, hot, young stars located in the centre of the bubble above the area shown in this image. The “steam” that appears to rise from the “mountains” is actually hot, ionised gas and hot dust streaming away from the nebula because of the relentless radiation. Protostellar jets shoot out from some of these young stars.  The youngest sources appear as red dots in the dark, dusty region of the cloud. Young stars and their dusty, planet-forming disks shine brightly in the mid-infrared, appearing pink and red.   | Photo Credit: NASA, ESA, CSA & Space Telescope Science Institute (STScI)
A dying star’s final “performance” in fine detail. The JWST has revealed new details of the Southern Ring Nebula, a planetary nebula catalogued as NGC 3132 that is 2,500 light years away. This is a complex system where two stars are locked in a tight orbit. Observing the nebula in mid-infrared wavelengths has shown the second star at its centre in far greater detail. 
Planetary nebulae—clouds of gas and dust expelled by dying stars—exist for thousands of years. During this period, the dimmer star at the centre of this scene was known to be sending out rings of gas and dust. 
In the image on the left the stars, and their layers of light, are prominent. The image on the right, shows for the first time that the second star is surrounded by dust. 
The brighter star is in an earlier stage of its stellar evolution, and as the stars continue to orbit one another, they “stir the pot” of gas and dust, creating a cosmic imagery of asymmetrical shells. Each shell represents an episode where the fainter star lost some of its mass. The widest shells of gas towards the outer areas of the image were ejected earlier. Those closest to the star are the most recent. 
A dying star’s final “performance” in fine detail. The JWST has revealed new details of the Southern Ring Nebula, a planetary nebula catalogued as NGC 3132 that is 2,500 light years away. This is a complex system where two stars are locked in a tight orbit. Observing the nebula in mid-infrared wavelengths has shown the second star at its centre in far greater detail.  Planetary nebulae—clouds of gas and dust expelled by dying stars—exist for thousands of years. During this period, the dimmer star at the centre of this scene was known to be sending out rings of gas and dust.  In the image on the left the stars, and their layers of light, are prominent. The image on the right, shows for the first time that the second star is surrounded by dust.  The brighter star is in an earlier stage of its stellar evolution, and as the stars continue to orbit one another, they “stir the pot” of gas and dust, creating a cosmic imagery of asymmetrical shells. Each shell represents an episode where the fainter star lost some of its mass. The widest shells of gas towards the outer areas of the image were ejected earlier. Those closest to the star are the most recent.  | Photo Credit: NASA, ESA, CSA & Space Telescope Science Institute (STScI)
Stephan’s Quintet. The term Stephan’s Quintet is best known from the formation of angelic figures in the 1946 classic film “It’s a Wonderful Life”, but the term is actually borrowed from astronomy. It refers to a visual grouping of five galaxies and is named after Edouard Stephan, a French astronomer who discovered it in 1877.
The JWST image shows the Quintet in a new light. It is the telescope’s largest image to date, covering a visual field that is about one-fifth of the moon’s diameter. The image shows sweeping tails of gas and dust and stars that are being pulled from several of the galaxies owing to gravitational interactions. The huge shock waves caused as one of the galaxies, NGC 7318B, smashes through the cluster is seen in extraordinary detail. 
Only four of the quintet are truly close together and engaged in a cosmic dance. The fifth and leftmost galaxy, called NGC 7320, is about 40 million light years from the earth, while the others are about 290 million light years away. 
The proximity of the quintet and tightness of the group provides astronomers a ringside view of the merging of and interactions between galaxies, which is a crucial part of their evolution. The topmost galaxy in the group, NGC 7319, harbours an active galactic nucleus, a supermassive black hole 24 million times the mass of the sun. It is actively pulling in material and puts out light energy equivalent to 40 billion suns. 
Stephan’s Quintet. The term Stephan’s Quintet is best known from the formation of angelic figures in the 1946 classic film “It’s a Wonderful Life”, but the term is actually borrowed from astronomy. It refers to a visual grouping of five galaxies and is named after Edouard Stephan, a French astronomer who discovered it in 1877. The JWST image shows the Quintet in a new light. It is the telescope’s largest image to date, covering a visual field that is about one-fifth of the moon’s diameter. The image shows sweeping tails of gas and dust and stars that are being pulled from several of the galaxies owing to gravitational interactions. The huge shock waves caused as one of the galaxies, NGC 7318B, smashes through the cluster is seen in extraordinary detail.  Only four of the quintet are truly close together and engaged in a cosmic dance. The fifth and leftmost galaxy, called NGC 7320, is about 40 million light years from the earth, while the others are about 290 million light years away.  The proximity of the quintet and tightness of the group provides astronomers a ringside view of the merging of and interactions between galaxies, which is a crucial part of their evolution. The topmost galaxy in the group, NGC 7319, harbours an active galactic nucleus, a supermassive black hole 24 million times the mass of the sun. It is actively pulling in material and puts out light energy equivalent to 40 billion suns.  | Photo Credit: NASA, ESA, CSA & Space Telescope Science Institute (STScI)