The James Webb telescope just got a detailed 'light fingerprint' of a single massive spot on a star far, far away.
arXiv · March 17, 2026 · 2603.15414
The Takeaway
While we see spots on our own Sun, this star hosts a 'polar spot' so massive it dominates the star's surface. Using JWST, astronomers were able to isolate the light from just that spot, measuring exactly how much cooler it is and how it reshapes the star's overall radiation.
From the abstract
TOI-3884 b is a rare super-Neptune transiting a fully convective M dwarf that hosts a persistent giant polar spot. Because the planet occults this active region during every transit, the system offers a unique laboratory to directly probe the stellar surface and spot properties. We present seven James Webb Space Telescope (JWST) transits of TOI-3884 b observed with NIRISS and NIRSpec, spanning 0.5--5.3$\mu$m. While all visits show a recurring spot-crossing signature, each transit exhibits a dist