James Webb's spacecraft, which began its scientific campaign about two months ago, has already demonstrated what it is capable of: today, 25 August, NASA and ESA announced that the space telescope was able to detect for the first time definitive evidence of the presence of carbon dioxide in the atmosphere of an exoplanet, a gas giant orbiting a star like the sun, 700 light years away.
The exoplanet in question is called WASP-39b and was discovered only in 2011 due to the reduced brightness of its star.
In this case, the method of analysis is called spectroscopy transmission. The spectrograph NIRSpec was used on board James Webb's spacecraft, provided by the European Space Agency. In the observed peak spectrum between 4.1 μm and 4.6 μm, it corresponds to the presence of carbon dioxide. This is the first evidence of the presence of this molecule on the planet outside the solar system.
Carbon dioxide Spectrum
"As soon as the data appeared on my screen, my attention was drawn to a huge figure of carbon dioxide. It was a special moment when we crossed an important threshold in the science of exoplanets." That's what Zafar Rustamkulov commented, a graduate student at Johns Hopkins University in the United States, and a member of the transit exoplanet team.
In the graph, each white point represents one observed wave length. The vertical grey stripes that pass through the center of each white point are uncertainty strips. The pik in the centre is carbon dioxide that can absorb more light from the star than other molecules. The blue line is an analytical model of researchers based on known exoplanet characteristics. The model presented here suggests that the planet consists mainly of hydrogen and helium with a small amount of water and carbon dioxide, as well as the presence of a thin cloud curtain.
The observations were conducted using a time series of bright objects NIRSpec PRISM, which uses a prism to disperse light from one bright object and measure the luminance of each wave length at specified intervals. The data were collected on 10 July 2022.
Because of its physical characteristics and frequent transits, the exoplanet was immediately the perfect object to study by means of a transit method. The discovery of carbon dioxide in the atmosphere of this exoplanet immediately gave rise to high hopes for both future research with James Webb and planetary science.
"," says team member Mike Line of the University of Arizona, United States."