“Somewhere something incredible is waiting to be known!” NASA Administrator Bill Nelson aptly quoted these words of Carl Sagan at a worldwide online event organised to release the first science images sent home by the James Webb Space Telescope (JWST). Whether this incredible revelation will have to do with the birth of stars; the most distant galaxies that formed within less than a billion years of the Big Bang; or the presence of biomarkers in the atmosphere of exoplanets (planets outside our solar system) only time can tell. The five images that were released were carefully selected, to align with the scientific goals of the mission, from about 700 pictures of the cosmos that JWST had collected so soon after its launch on December 25, 2021.
In the order in which they were released, the five images were the following: A deep field picture in which the telescope gazed into a galaxy cluster that is about 13.1 billion light years away; a hot gaseous exoplanet that is about 1,000 light years away – a spectrum of its atmosphere which carried the chemical fingerprint of water vapour; a violent explosion that marked the death of a massive star, known as the Southern Ring; a group picture of five galaxies – Stephan’s Quintet, about 300 million light years away; a picture of Carina nebula, which is 7,600 light years away, showing crops of new stars being born.
The extent of clarity in these images could be felt as zooming into the images revealed more and more detail of the stars, galaxies and gaseous dust.
“It’s a set of amazing images. Every image looks so beautiful but it is also full of information,” says Jessie Jose from the physics department of Indian Institute of Science Education and Research (IISER), Tirupati. She is a member of a large collaboration whose proposal for the study of start formation has been admitted by the JWST. “Among these pictures, the one of Carina Nebula is the one I was most moved by. It is a star-forming region that is 1,700 light years away from the Earth,” she says. “If you zoom into it you will see lots of features – such as nebulas, lots of new born stars, jet outflows from these young stars. it’s a star-formation nursery.”
The electromagnetic spectrum is made up of light of many wavelengths ranging from x-ray, ultraviolet and visible to infrared and mid-infrared wavelengths, to name a few. On earth we mostly get only the visible light of the sun, as our atmosphere filters out the others. Similarly, every celestial body emits light in all wavelengths. JWST has onboard instruments that sense light in the infrared, mainly 0.6 micron to 28 microns. It has multiple cameras in this regime. Some of these cameras capture images while others capture the spectral details. Since infrared light can penetrate the clouds of dust that surround celestial objects, many features that cannot be imaged with visible light cameras would show themselves to the JWST.
“There have been other missions like COBE, Planck, WMAP, that looked deep into space and get information about what happened a few hundred million yeaars after the Big Bang. But these were not images of the stars and galaxies that formed in the beginning. JWST will be able to give us details about those first stars and galaxies that formed in the universe post Big Bang,” she says.
Manoj Puravankara from Tata Institute of Fundamental Research, Mumbai, is also a part of another team that has been selected to study stars being born that have masses in the range 0.1 to 12 times the mass of our sun. He says, “JWST’s unprecedented sensitivity, angular resolution and spectral resolution allow us to study various mass flows that shape and regulate the formation of stars and planetary systems.”
