Dusty Debris Disk Around AU Mic (Annotated)

The NASA/ESA/CSA James Webb Space Telescope has imaged the inner workings of a dusty disk surrounding a nearby red dwarf star. These observations represent the first time the previously known disk has been imaged at these infrared wavelengths of light. They also provide clues to the composition of the disk.

These two images are of the dusty debris disk around AU Mic, a red dwarf star located 32 light-years away in the southern constellation Microscopium. Scientists used Webb’s Near-Infrared Camera (NIRCam) to study AU Mic. NIRCam’s coronagraph, which blocked the intense light of the central star, allowed the team to study the region very close to the star. The location of the star, which is masked out, is marked by a white, graphical representation at the center of each image. The region blocked by the coronagraph is shown by a dashed circle.

Webb provided images at 3.56 microns (top, blue) and 4.44 microns (bottom, red). The team found that the disk was brighter at the shorter or “bluer” wavelength, likely meaning that it contains a lot of fine dust that is more efficient at scattering shorter wavelengths of light.

The NIRCam images allowed the researchers to trace the disk, which spans a diameter of 60 astronomical units (9 billion kilometers), as close to the star as 5 astronomical units (740 million kilometers) – the equivalent of Jupiter’s orbit in our solar system. The images were more detailed and brighter than the team expected, and scientists were able to image the disk closer to the star than expected.

While detecting the disk is significant, the team’s ultimate goal is to search for giant planets in wide orbits, similar to Jupiter, Saturn, or the ice giants of our solar system. Such worlds are very difficult to detect around distant stars using either the transit or radial velocity methods.

These results are being presented in a press conference at the 241st meeting of the American Astronomical Society. The observations were obtained as part of Webb’s Guaranteed Time program 1184.

[Image Description: The visual shows two bright lines, representing the dusty debris disc around the red dwarf star AU Mic. The glowing line on top is blue, representing 3.56 microns and appears brighter, and the glowing line on bottom is red, representing 4.44 microns.]