The James Webb Infrared Space Telescope has obtained new live images of the outsized system around the star HR 8799. Observational data allowed to recalculate the parameters of the outermost exoplanet, detect the innermost component of the circumstellar disk and refute the existence of a fifth exoplanet in the system. A preprint of the work has been published on arXiv.org. Direct observations of exoplanets provide a very complex but effective way to detect and study exoplanets. It is more sensitive to giant exoplanets with wide orbits (semi-axial length greater than five astronomical units) that are difficult to observe using transit or radial velocity methods, allowing an overview of the source their origin and evolution.
A team of astronomers led by Anthony Boccaletti of the Paris Observatory has published mid-infrared observations of the exoplanet system HR 8799 using MIRI’s James Webb instrument in coronal mode. HR 8799 is located 133.3 light-years from the Sun in the constellation Pegasus. It is a young (about thirty million years old) star of the Lambda Boötes type, 1.5 times more massive than the Sun, and has four known gas giants, five to ten times more massive than Jupiter . Scientists have redefined the temperature and effective radius of exogiant HR 8799b, the farthest from the star, to be 950 to 1,100 kelvins and 0.86 to 1.07 Jupiter radii, respectively. The researchers also detected radiation from the hot inner component of the circumstellar dust disk, located at a distance of 6 to 15 astronomical units from the star.
Another important result of this work was the failure to detect a fifth exoplanet in the system, whose existence had been previously assumed. Instead, the point source found in MIRI’s field of view is a distant barred spiral galaxy with a redshift value of z ≈ 1.