James Webb looks at TRAPPIST-1, a star system full of Earth-like planets

The James Webb Space Telescope is beginning to look at the most exciting candidates for life elsewhere in the universe – a group of exoplanets in the star system known as TRAPPIST-1.

This means that in the coming years, astronomers can expect a wealth of data from a host of planets outside our solar system that will help answer the age-old question: Are we alone in the universe?

Webb stunned the world in recent weeks after NASA released its first set of appropriate observations that included the deepest infrared image of the universe ever taken.

While the telescope’s stunning, color images of distant cosmic objects capture the public imagination, it can be easy to overlook the wealth of raw data that the telescope has and will continue to collect.

TRAPPIST-1
An artist’s impression of the TRAPPIST-1 system, posted online by NASA in 2017. TRAPPIST-1 is one of the most impressive groups of exoplanets – exoplanets – that we know of.
NASA/JPL-Caltech

Almost immediately after he was able to make scientific observations, Webb began studying the TRAPPIST-1 system as a priority. TRAPPIST-1 is a red dwarf star located 12 parsecs (39 light years) away from our sun and has intrigued astronomers since its discovery in 2017.

That’s because TRAPPIST-1 has been found to contain at least seven rocky exoplanets — planets found outside the solar system — orbiting it with sizes and masses similar to those on Earth. Moreover, initial observations suggested that some planets might have temperatures low enough to support the presence of liquid water hypothetically.

“There are other terrestrial or temperate planets or both, but they are usually too far away or around a star too large to really allow us to study them,” Julian de Witt, associate professor of Earth, Atmosphere and Planetary sciences at the Massachusetts Institute of Technology and part of the team said. Who discovered the TRAPPIST-1 system NEWSWEEK.

“So these are the only windows we have, perhaps, to the atmospheres of other habitable terrestrial planets, and that’s what really sets them apart.”

However, due to technological limitations, we have not yet been able to ascertain the crucial property of these planets: whether or not they have an atmosphere. That is, until Webb climbed to the scene.

said Michael Gillon, an exoplanet researcher at the University of Liege in Belgium who led the team that discovered the TRAPPIST-1 system.

Tell NEWSWEEK: “You really need a very large telescope far from Earth, you can observe it for hours or days if necessary, and it operates in a large wavelength range in the infrared [spectrum], because that’s where all the molecular spectral features we’re looking for are located. And James Webb is exactly what I’m talking about.”

For De Wit, the technological step forward made with Webb cannot be overstated. “In terms of information content, we are very much moving from listening to radio to television,” he said.

split light

The method that scientists will use to find out if the TRAPPIST-1 planets have atmospheres is called transit spectroscopy. It works by collecting sunlight passing around a nearby planet and splitting that light into a spectrum – just like how a prism splits white light into a rainbow.

If this sunlight passes through the planet’s atmosphere on its way to Earth, there will be telltale signals in that light’s spectrum.

“So you have fingerprints of the chemical signature of the atmosphere that appear in your data and your spectroscopic data,” Gillon said.

James Webb Space Telescope
Illustration of the James Webb Space Telescope in space. The telescope, which was launched in December last year, began conducting scientific operations. Image license: https://creativecommons.org/licenses/by/2.0/
NASA GSFC / CIL / Adriana Manrique Gutierrez

The search will be done in steps. First, Webb astronomers will ascertain if any of the TRAPPIST-1 planets actually possess atmospheres — a massive development in and of itself.

Second, work will begin to find out what each of these spheres consists of. A process that de Wit described as “like peeling an onion”.

“Something worth noting is that something can be easily detected just because it has very powerful features, but it may be at a very, very low amount,” he added. “So we’ll start to find the molecular features, which is cool. But then the next step will be for us to have enough data so that we can start discussing how much of this is, and then we can even start extracting information about temperature, as a function of height and pressure” .

Then, Webb’s team can begin to deduce details about the surface conditions and processes that could have led to those atmospheric components being present in the first place.

“It’s like your favorite TV show, and you have to wait a week for the next episode,” de Witt said. “In that case, you may have to wait a year to get the next episode.”

get gas

There are several components of the atmosphere that may be of interest to scientists studying the TRAPPIST-1 planets – water vapor may be among the first that come to mind – but for Gilon, methane will be the biggest component.

“Methane, as we know, has a very short life,” he said. “In such an atmosphere, its molecules disappear very quickly. So if you have large amounts of methane in the atmosphere of one of the TRAPPIST-1 planets, with the atmosphere also being rich in carbon dioxide or ozone, that means there is a very large amount of methane in the atmosphere. Methane is a great source of methane and we don’t know a lot of abiotic sources, but we do know that life can produce methane.

“We think that before Earth’s atmosphere was very rich in oxygen, thanks to the advent of photosynthesis, methane was present in abundance in Earth’s atmosphere because there were some bacteria that produced a lot of methane at that time.

“So if we find methane that will be very exciting.”