This illustration shows what exoplanet WASP-39 b could look like, based on current understanding of … [+] the planet. WASP-39 b is a hot, puffy gas giant with a mass 0.28 times Jupiter (0.94 times Saturn) and a diameter 1.3 times greater than Jupiter, orbiting just 0.0486 astronomical units (7,200,000 kilometres) from its star. The star, WASP-39, is fractionally smaller and less massive than the Sun. Because it is so close to its star, WASP-39 b is very hot and is likely to be tidally locked, with one side facing the star at all times. NASA’s James Webb Space Telescope’s exquisitely sensitive instruments have provided a profile of WASP-39 b’s atmospheric constituents and identified a plethora of contents, including water, sulphur dioxide, carbon monoxide, sodium and potassium. This illustration is based on indirect transit observations from Webb as well as other space and ground-based telescopes. Webb has not captured a direct image of this planet. [Image Description: This image shows an artist’s impression of the planet WASP-39 b and its star. The planet has a fuzzy orange-blue atmosphere with hints of longitudinal cloud bands below. The left quarter of the planet (the side facing the star) is lit, while the rest is in shadow. The star is bright yellowish-white, with no clear features.]
NASA, ESA, CSA, J. Olmsted (STSc
The James Webb Space Telescope (JWST) has revealed a distant alien planet to be cloudy with a chance of active chemistry. WASP-39 b, aka “Bocaprins,” orbits a star slightly smaller than our Sun about 700 light-years distant in the constellation of Virgo in our Milky Way galaxy.
A so-called “hot Saturn” planet, Bocaprins was first examined in summer when JWST began its science observations, but it’s now revealed the planet’s full chemical profile—and made some unique discoveries.
Splitting the planet’s faint light into a spectrum scientists can see the telltale signs of atoms, molecules and active chemistry involving water, sulphur dioxide, carbon monoxide, sodium and potassium. It’s thought to have a fuzzy orange-blue atmosphere with cloud bands below.
Both Webb and the Hubble Space Telescope have previously revealed one-off ingredients of this hot planet’s atmosphere, but this “full menu” is a first. The data also revealed that the planet’s clouds could be broken up rather than a uniform blanket.
This is great news for a scientific community desperate to explore smaller, rockier and more Earth-like planets such as those in the TRAPPIST-1 system.
The atmospheric composition of the hot gas giant exoplanet WASP-39 b has been revealed by the … [+] NASA/ESA/CSA James Webb Space Telescope. This graphic shows four transmission spectra from three of Webb’s instruments operated in four instrument modes. All are plotted on a common scale extending from 0.5 to 5.5 microns. A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves in front of the star, to the unfiltered starlight detected when the planet is beside the star. Each of the data points (white circles) on these graphs represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. Wavelengths that are preferentially absorbed by the atmosphere appear as peaks in the transmission spectrum. The blue line is a best-fit model that takes into account the data, the known properties of WASP-39 b and its star (e.g., size, mass, temperature), and assumed characteristics of the atmosphere. Researchers can vary the parameters in the model – changing unknown characteristics like cloud height in the atmosphere and abundances of various gases – to get a better fit and further understand what the atmosphere is really like. At upper left, data from NIRISS shows fingerprints of potassium (K), water (H2O), and carbon monoxide (CO). At upper right, data from NIRCam shows a prominent water signature. At lower left, data from NIRSpec indicates water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO). At lower right, additional NIRSpec data reveals all of these molecules as well as sodium (Na). [Image Description: Graphic titled “Hot Gas Giant Exoplanet WASP-39 b Atmosphere Composition.” The graphic includes four graphs—transmission spectra—arranged in a 2 by 2 grid with an illustration of the planet and its star in the background.]
NASA, ESA, CSA, J. Olmsted (STSc
“This is the first time we have seen concrete evidence of photochemistry — chemical reactions initiated by energetic stellar light — on exoplanets,” said Shang-Min Tsai, a researcher at the University of Oxford in the U.K. and lead author of the paper explaining the origin of sulphur dioxide in WASP-39 b’s atmosphere. “I see this as a really promising outlook for advancing our understanding of exoplanet atmospheres with [this mission].”
Earth-like Bocaprins certainly is not. Bocaprins is an odd planet. It orbits very close to its host star and appears to be tidally locked—as the Moon is to Earth—so has one super-hot side and one super-cold. It’s actually eight times closer than Mercury is to our Sun, although it’s about 1.3 times greater in diameter than Jupiter.
“We observed the exoplanet with several instruments that together cover a broad swath of the infrared spectrum and a panoply of chemical fingerprints inaccessible until JWST,” said Natalie Batalha, an astronomer at the University of California, Santa Cruz, who contributed to and helped coordinate the new research. “Data like these are a game changer.”
