Researchers confirmed an exoplanet using NASA’s James Webb Space Telescope for the first time. Designated formally as LHS 475 b, this celestial body closely approximates Earth's dimensions, clocking in at 99% of Earth's diameter. Among the myriad of telescopic instruments in operation, the James Webb Space Telescope stands unparalleled in its capability to scrutinize the atmospheres of exoplanets. The team attempted to assess what is in the planet’s atmosphere by analyzing its transmission spectrum.
A transmission spectrum characterized by a consistent horizontal alignment, as illustrated in this instance, offers substantial intrigue and valuable insight. Augmented by the Near-Infrared Spectrograph (NIRSpec) component of NASA's James Webb Space Telescope, researchers observed the exoplanet LHS 475 b on August 31, 2022. As this spectrum shows, Webb did not observe a detectable quantity of any element or molecule. The data points (represented as white dots) align with a uniform spectrum indicative of an atmosphere-less planet (as illustrated by the yellow line).The purple line represents a pure carbon dioxide atmosphere and is indistinguishable from a flat line at the current level of precision. The green line represents a pure methane atmosphere, which is not favored since if methane were present, it would be expected to block more starlight at 3.3 microns.
Subsequent to these initial findings, the research team is slated to procure supplementary spectra. Additionally, the Webb telescope divulged that the planet registers a temperature few hundred degrees higher than that of Earth. Consequently, the potential identification of clouds may steer researchers towards an inference that the planet more closely resembles Venus – characterized by a carbon dioxide atmosphere enshrouded in dense clouds.
The researchers also confirmed that the planet completes an orbit in just two days, information that was almost instantaneously revealed by Webb’s precise light curve.
Although LHS 475 b is closer to its star than any planet in our solar system, its red dwarf star is less than half the temperature of the Sun, leading researchers to entertain the idea of an atmosphere. The team’s results were presented at a press conference of the American Astronomical Society (AAS) on Wednesday, Jan. 11, 2023.
Source: NASA. "NASA’s Webb Confirms Its First Exoplanet". https://www.nasa.gov/feature/goddard/2023/nasa-s-webb-confirms-its-first-exoplanet. Jan 11, 2023. [Accessed: Jan 11, 2023].
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