'We can soon study stars that formed during the Big Bang'

THE JAMES WEBB SPACE TELESCOPE AMAZED THE WORLD ON JULY 12 WITH ITS FIRST IMAGES OF THE UNIVERSE. ASTROPHYSICIST JESSY JOSE OF THE INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH, TIRUPATI, WILL SOON USE THE LARGEST AND MOST POWERFUL TELESCOPE IN THE WORLD TO STUDY THE EARLY STAGES OF STARS. SHE TELLS ROHINI KRISHNAMURTHY WHAT MAKES THIS DEEPSPACE VIEWING TOOL ONE OF A KIND

- ROHINI KRISHNAMURTHY

The James Webb telescope has released spectacular images of deep space. What insights do they provide?

The quality of the images is excellent. If you zoom into each image, a lot of features become visible. For instance, studying the image of Stephan's Quintet [290 million light years away from Earth], where galaxies are merging, will tell us how stars are formed and how they disturb galaxies in the process. This is important as the merging of galaxies is common. Our own Milky Way and Andromeda are moving towards each other and are expected to merge after several billion years.

The colours in the captured images tell us about the temperature. The bubble in the Southern Ring planetary nebula [2,500 light-years away] image, for instance, has red on the outside and blue on the inside, which shows the temperature distribution.

How does it synthesise the images?

The James Webb telescope (JWST) has multiple filters that capture images at different wavelengths. The individual images are in black and white. They are then combined, and colours are assigned based on the wavelength. A longer wavelength is generally assigned red, while a shorter one is assigned blue. Green falls in the middle. We can assign more colours as well when more filters are used. The colour of a region is a function of temperature.