James Webb Space Telescope just detected carbon dioxide on an exoplanet

It's a big step forward in understanding exoplanets.
Sade Agard
Exoplanet WASP-39 b
Exoplanet WASP-39 b.

Wikimedia Commons 

Humanity's giant space telescope has captured evidence of carbon dioxide in a planet outside of the solar system for the first time.

According to a Thursday press release on NASA TV, for the first time, NASA's James Webb Telescope has captured clear evidence of carbon dioxide in the atmosphere of a gas giant exoplanet called WASP-39 b.

The detection was made using Webb's Near-Infrared Spectrograph (NIRSpec) and took the form of a small bump between 4.1 and 4.6 microns on the spectrum related to the exoplanet's atmosphere. The evidence helps shine a light on how planets are formed.

"As soon as the data appeared on my screen, the whopping carbon dioxide feature grabbed me,” Zafar Rustamkulov, a graduate student at Johns Hopkins University and member of the JWST Transiting Exoplanet Community Early Release Science team, which undertook this investigation, said in the press release. “It was a special moment, crossing an important threshold in exoplanet sciences.”

It's a key moment for the James Webb Space Telescope. Launched on December 25, 2021, the telescope has a giant 21-foot (6.5-meter) gold-coated mirror that's used to peer further into space with higher detail than ever before. Last month, the telescope stunned the world when NASA released its first images.

The NIRSpec, which captured the latest carbon dioxide readings, works through filtered starlight, which is based on the concept that different gases absorb various combinations of colors. The brightness differences in these can be analyzed by researchers when cross-referenced with a spectrum of wavelengths. In this way, the composition of an atmosphere can be determined.

Why WASP-39 b? The planet, first discovered back in 2011, is classed as a "transiting" one. In other words, it has an orbit that can be seen edge-on as opposed to from above, observations of starlight are particularly more convenient for researchers. Additionally, WASP-39 b tends to undergo frequent transits and with its inflated atmosphere makes quite the smooth target for transmission spectroscopy.

The find is significant because measurements in this part of the transmission spectrum — i.e. in the 3 to 5.5-micron range — for exoplanets play a crucial role in measuring the presence of gases like water, methane, and carbon dioxide. The extent of these differences in brightness observed for WASP-39 b has never been measured at any other observatory to date.

“Detecting such a clear signal of carbon dioxide on WASP-39 b bodes well for the detection of atmospheres on smaller, terrestrial-sized planets,” Natalie Batalha of the University of California at Santa Cruz and leader of the research team said in the press release.

James Webb Space Telescope just detected carbon dioxide on an exoplanet
Data captured from the telescope's near-infrared spectrometer on July 10, 2022.

Illustration: NASA , ESA, CSA, and L. Hustak (STScI); Science: The JWST Transiting Exoplanet Community Early Release Science Team

A carbon-containing exoplanet 700 light years away

Orbiting a sun-like star 700 light years away, the observation of carbon dioxide was detected on the hot gas giant planet, WASP-39 b, having a mass roughly one-quarter that of Jupiter, a diameter 1.3 times greater than Jupiter.

Unlike the cooler, more compact gas giants in our solar system, WASP-39 b orbits very close to its star containing temperatures of about 1600 degrees Fahrenheit. As a result of this proximity, the exoplanet has a noticeable puffiness to it and takes just over four Earth days to complete one full circuit.

Planets like WASP-39 b are described as 'transiting'. Due to the exoplanet's orbit characteristically observed edge-on rather than from above, researchers can gain opportunities for insights into their planetary atmospheres.

Previous measurements from telescopes like Hubble also revealed the presence of water vapor and potassium. With this latest discovery, James Webb has again demonstrated its ability to advance scientific understanding of the universe.

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