Scientists find signs of carbon dioxide on an exoplanet

There’s hardly anyone left who don’t know about the harmful effects of greenhouse gases such as carbon dioxide (CO2), one of the major contributors of climate change. While the earthlings continue to work towards reducing carbon footprints, CO2 has made its hazardous presence felt in a planet outside our solar system too! This has recently been discovered by NASA’s James Webb Space Telescope and has taken the astronomical community by storm. The findings have been published in the scientific journal Nature.  

Carbon dioxide on exoplanet WASP-39b 
Located 15,00,000 kilometres away from the Earth, the James Webb Space Telescope has detected the first clear evidence of carbon dioxide in the atmosphere of an exoplanet (planet that is situated outside the solar system) called WASP-39b. Discovered in February 2011 as part of the Wide Angle Search for Planets (WASP) project, WASP 39-b was also in the news in 2018 when both the Hubble and the Spitzer space telescopes found large quantities of water vapour, sodium and potassium on it. However, they couldn’t manage to trace carbon dioxide as carbon absorbs light at longer and more infrared wavelengths than water vapour and the other substances. Turns out, only James Webb Space Telescope’s Near-Infrared Spectrograph is equipped to detect it through the process of transmission spectroscopy.  

Wondering what it means? Here’s a walkthrough. Transmission spectroscopy refers to the process by which different gases absorb different combinations of colours across a spectrum of wavelengths, something that can be observed in the spectrum of transmitted starlight from behind the exoplanet. And guess what? By looking at the missing colours, astronomers can very well deduce which gases are present in its atmosphere and the ones that aren’t. This is how CO2 was detected when the Spectrograph detected a range of 4.1 to 4.6 microns, that’s unique to the gas.  

Interestingly, the new findings will help scientists understand the formation and evolution of the exoplanet with relation to its host star. It will also help them figure out the atmospherical characteristics of such small extra solar planets. Earlier, when the planet was discovered using transit method (when it was observed from Earth, it was seen passing in front of its star), it was difficult for the scientists to detect the nature of the planet as it dimmed the light of its star, but the latest finding is expected to fix that as well.   

Meet WASP-39b, the faraway gas giant 
That’s right! This extra solar planet is a gas giant that orbits a sun-like star located more than 700 light years away from the Earth in the Virgo constellation. This alien planet has a mass equivalent to a quarter of Jupiter’s and is approximately 1.3 times its diameter. As it orbits too close to its host star, it has a burning surface temperature that is estimated to be around 900 degrees Celsius. In fact, it is about one-eighth the distance from its star as Mercury is from the sun, thus completing a revolution in just four days.