The James Webb Space Telescope discovered its first new exoplanet, an Earth-sized rocky planet called LHS 475 b. Just 41 light-years away, the planet orbits very close to a small, dim star, completing one full orbit in just two days. LHS 475 b is a roughly Earth-sized rocky exoplanet orbiting very close to a small, faint star. Many exoplanets have been discovered before, but this is the first time that researchers are able to study the planet’s atmosphere.
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A special discovery that only James Webb could handle
The discovery that in American Astronomical Society meeting (AAS) presented on Wednesday, Jan. 11 (Dec. 21), is particularly important because most discovered exoplanets are usually large gas giants similar to Jupiter. Earth-like planets are harder to detect with most telescopes because they are much smaller, less than one-tenth the diameter of a giant planet.
Previous research with NASA’s Transiting Exoplanet Survey Satellite, another space telescope launched in 2018 specifically to search for exoplanets, had suggested that there was a possible planet candidate in the system. The James Webb telescope was able to confirm the presence of this planet with observations made in August and September 2022 (summer 1401).
This is just James Webb’s first hunt
The fact that the James Webb telescope was able to detect this planet indicates that it will be able to detect Earth-like planets in the future. And even more, it should be able to detect their atmospheres—something other telescopes can’t do with planets this size.
The ultimate goal of much current exoplanet research is to understand the atmospheres around exoplanets. To better understand whether some planets are habitable, astronomers need to study their atmospheres, which can have a profound effect on factors such as surface temperature.
Jakob Lustig Jager of the Johns Hopkins University Applied Physics Laboratory said at the AAS meeting:
“In the next few years and eventually decades, the search for life in exoplanets will rely fundamentally on the accurate description of exoplanet atmospheres. And the first step in this journey is to detect the presence of exoplanet atmospheres.
How is a planet identified several light years away?
Although the James Webb telescope should be able to detect the atmospheres of exoplanets, the task remains challenging. Exoplanets are much smaller than stars and emit much less light, so they are rarely detected directly. Instead, astronomers study host stars, looking for small deviations in their brightness or motion that indicate the presence of a planet orbiting them.
Lustig Lager further explained that due to these conditions, the James Webb telescope will probably only be able to detect the atmospheres of rocky planets that revolve around very small stars called red dwarfs. In some ways, this is good for hunting for habitable planets, since these rocky worlds are similar in size to Earth. However, these types of planets orbit their stars much closer than Earth does to the Sun, and are therefore much hotter. When a planet gets this close to its host star, its atmosphere can be destroyed by the star’s heat and radiation.
In the case of the recently discovered exoplanet LHS 475 b, the James Webb telescope observed two transits (where the planet passes in front of its host star, causing a temporary and very small decrease in the star’s brightness), both of which indicate the presence of the planet. and allowed the team to determine its radius.
They also used a technique called transmission spectroscopy to probe its atmosphere, and while they couldn’t definitively confirm the presence of an atmosphere, they were able to rule out several possibilities. The findings show that this planet does not have a hydrogen-dominated atmosphere like Jupiter or a pure methane atmosphere. It could possibly have a carbon dioxide-dense atmosphere like Venus, or perhaps no atmosphere at all – because its atmosphere has been stripped away by its star.
Nothing is certain yet
Associate Researcher Erin May In a statement he said:
The data of this observatory are beautiful. The telescope is so sensitive that it can easily detect a wide range of molecules, but we still cannot draw any definitive conclusions about the planet’s atmosphere.
The research team plans another observation of the planet this summer using the James Webb Telescope, which will help them learn more. And this research shows just how powerful James Webb’s tool is for learning about exoplanets.
“Although we don’t detect atmospheres in this case, our measurements meet the critical requirements to detect the atmospheres of Earth-sized planets. “So it’s a very exciting time,” Lusting-Jaeger said. “We are just beginning to scratch the surface of what is possible with the James Webb Telescope.”
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