In an observational feat of remarkably high precision, scientists used a new technique with NASA’s James Webb Space Telescope to capture the shadows of starlight cast by the thin rings of Chariklo. Chariklo is a small object, but the largest of the known Centaur population, located more than 2 billion miles away beyond the orbit of Saturn. Chariklo is only 250 kilometers (160 miles, or ~51 times smaller than Earth) in diameter and its rings orbit at a distance of about 400 kilometers (250 miles) from the center of the body.
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Editor’s Note: This post highlights data from Webb science in progress, which has not yet been through the peer-review process.
On October 18, 2022, we used Webb’s Near-Infrared Camera (NIRCam) instrument to closely monitor the star Gaia DR3 6873519665992128512, and watch for the tell-tale dips in brightness indicating an occultation had taken place. The shadows produced by Chariklo’s rings were clearly detected, demonstrating a new way of using Webb to explore solar system objects. The star shadow due to Chariklo itself tracked just out of Webb’s view; this appulse (the technical name for a close pass with no occultation) was exactly as had been predicted after the last Webb course trajectory maneuver.
The Webb occultation light curve, a graph of an object’s brightness over time, revealed that the observations were successful! The rings were captured exactly as predicted. The occultation light curves will yield interesting new science for Chariklo’s rings. Pablo Santos-Sanz explains: “As we delve deeper into the data, we will explore whether we cleanly resolve the two rings. From the shapes of rings’ occultation light curves, we also will explore the rings’ thickness, the sizes and colors of the ring particles, and more. We hope gain insight into why this small body even has rings at all, and perhaps detect new fainter rings.”
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The chaotic merging galaxies II ZW 96 have been examined in two distinct wavelengths in these images from the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope.
The image on the left was taken by Hubble’s Advanced Camera for Surveys and gives a view over the visible-light spectrum of this merger, clearly showing the starburst systems that have formed between the two galactic cores with their older stars.
The image on the right, Webb’s image from the Near-InfraRed Camera shines particularly brightly in infrared light. The star-forming regions which have been activated by the galactic tumult are particularly luminous in the infrared, which placed ZW II 96 as one of Webb’s first targets.
Credit: ESA/Webb, NASA & CSA, L. Armus, A. Evans; the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration
