New Observations of HR 8799 System by JWST’s MIRI Instrument Reveal Details of Exoplanets
The James Webb Space Telescope (JWST) has recently observed the HR 8799 system, a distant solar system located about 133 light-years away. The observations were made using the Mid-Infrared Instrument (MIRI) and its coronagraph, which enabled high-contrast imaging. The results of these observations are presented in a new paper titled “Imaging detection of the inner dust belt and the four exoplanets in the HR 8799 system with JWST’s MIRI coronagraph,” authored by Anthony Boccaletti from the LESIA, Observatoire de Paris, France.
HR 8799 is an intriguing system due to its young age and the presence of four massive planets: HR 8799 b, c, d, and e. These planets were discovered 15 years ago through direct imaging and have orbits ranging from 16 to 71 astronomical units away from the star. They are all massive, with masses between 5.7 and 9.1 Jupiter masses, and have radii of about 1.2 Jupiter radii.
The JWST’s MIRI instrument provided a new perspective on the HR 8799 system, yielding a different vision compared to previous observations in the near-infrared. The observations confirmed that these four giant planets are indeed planets and not brown dwarfs. Their temperatures range from 900 K to 1300 K, with planet b being fainter and cooler than the others. The observations also identified the presence of water (H2O) and carbon monoxide (CO) in the planets’ atmospheres.
One of the main objectives of the study was to better characterize the planetary atmospheres and determine if ammonia, a biosignature on terrestrial planets, could be detected. However, the current data was inconclusive regarding the presence of ammonia. The authors highlighted the need for further observations and improvements in interpreting the results.
In addition to studying the exoplanets, the JWST observations also shed light on the HR 8799 system’s debris disk. Previous theories suggested the presence of a fifth planet or a dust clump causing the inner edge of the outer debris belt. However, the JWST’s MIRI instrument revealed that the object was a background feature, putting an end to the debate.
Overall, the observations of the HR 8799 system using the JWST’s MIRI instrument provide valuable insights into the nature of these exoplanets and their atmospheres. The study also highlights the potential of the MIRI instrument for future investigations of young exoplanetary systems.