A team of researchers led by Jacob Lustig-Yaeger and Kevin Stevenson at the Johns Hopkins University Applied Physics Laboratory (APL) used the James Webb Space Telescope to identify an exoplanet roughly the size of Earth. The results of the research that it did was announced at the 241st meeting of the American Astronomical Society. This is the first time that the existence of an exoplanet has been confirmed by observations with the Webb Space Telescope.
The diameter is 99% of the earth. It is expected that future observations will provide conclusions about the presence and composition of the atmosphere.
The research team reported on the exoplanet “ LHS 475 b ” about 41 light years away in the direction of “ Hachibungi ” in the southern sky. LHS 475 b has a diameter of 99% that of Earth, and it has been confirmed that it orbits its main star, the red dwarf star LHS 475, every two days.
As seen from Earth, LHS 475 b periodically makes “transits” across the front of its star. During the transit, the planet obscures part of the star, so its brightness is only slightly dimmer. By examining the changes in brightness and the light spectrum (intensity of each wavelength of electromagnetic waves) in detail, we can obtain information such as the exoplanet’s diameter, orbital period, presence or absence of atmosphere, and chemical composition.
The research team carefully examined observational data from NASA’s exoplanet probe TESS, which uses transit to detect exoplanets, and selected LHS 475 as a target for observations by the Webb Space Telescope. I chose
The second image shows observation data (purple) from the Webb Space Telescope’s Near-Infrared Spectrometer (NIRSpec) that clearly captures the change in brightness of LHS 475 when LHS 475 b transits. shown. The data was obtained during an observation conducted on August 31, 2022.
In addition, by performing spectroscopic observations to obtain the spectrum of the host star when the exoplanet passes in front of the host star, we can know what substances exist in the planet’s atmosphere. The third image below shows the transmission spectrum of LHS 475 b (the spectrum of the main star’s light that has passed through the exoplanet’s atmosphere). At the time of the announcement, no conclusions have been drawn about the presence or absence of the atmosphere and chemical composition of LHS 475 b, but at least it is believed that there is no thick atmosphere mainly composed of methane like Saturn’s satellite Titan.
However, the atmosphere, which is mainly composed of carbon dioxide like Mars, is difficult to detect because it is thin, and it is difficult to distinguish it from the absence of an atmosphere, so the research team will add more detailed data in the summer of 2023. We are planning to make an observation. Data obtained so far indicate that the surface temperature of LHS 475 b is about 200 to 300 degrees Celsius warmer than that of Earth, and if the presence of carbon dioxide atmosphere and clouds is detected, Venus It seems that there is also a possibility to conclude that it is a planet similar to .
Confirmation of LHS 475 b based on Webb Space Telescope data is just the beginning. It is said that the main subject of research in the past has been gas giant planets, partly due to limitations in observation methods, but this result once again demonstrates the high accuracy of the Webb Space Telescope, which can identify smaller exoplanets. I was. Lustig-Yaeger and Stevenson hope that observations using the Webb Space Telescope will discover more rocky planets in the future.
- Image Credit: Illustration: NASA, ESA, CSA, Leah Hustak (STScI); Science: Kevin B. Stevenson (APL), Jacob A. Lustig-Yaeger (APL), Erin M. May (APL), Guangwei Fu (JHU), Sarah E. Moran (University of Arizona)
- NASA – NASA’s Webb Confirms Its First Exoplanet
- ESA – Webb confirms its first exoplanet
- STScI – NASA’s Webb Confirms Its First Exoplanet
- ESA/Webb – Webb Confirms Its First Exoplanet
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