James Webb Space Telescope Feed Post

JWST-TST High Contrast: Asymmetries, dust populations and hints of a collision in the Beta Pictoris disk with NIRCam and MIRI

The Beta Pic debris disk as seen with NIRCam and MIRI. The top 6 panels for NIRCam result from MCRDI PSF subtraction as described in section 2.5.2, while the bottom two panels for MIRI are from classical PSF subtractions as described in section 2.5.1. In the NIRCam data, looking closely the planet ß Pic b can be seen just to the left (NE) of the occulted star (indicated with an arrow in the F300M data), along with the edge-on debris disk and its subtle warp already known from prior observations. In the MIRI data, a highly asymmetric curved feature we dub the “cat’s tail” is seen to the west (SW), apparently bending sharply away from the disk plane (see Fig. 4 and Sect. 3.2). A mask has been applied to the F2300C image only to block the pixels behind the opaque classical Lyot occulter and its supports. All images are shown rotated 60.9° to align the main disk major axis horizontally, on identical asinh stretches and identical spatial scales, though with a larger vertical field of view shown for the more extended nebulosity seen with MIRI. Abstract: We present the first JWST MIRI and NIRCam observations of the prominent debris disk around Beta Pictoris. Coronagraphic observations in 8 filters spanning from 1.8 to 23~µm provide an unprecedentedly clear view of the disk at these wavelengths. The objectives of the observing program were to investigate the dust composition and distribution, and to investigate the presence of planets in the system. In this paper, we focus on the disk components, providing surface brightness measurements for all images and a detailed investigation of the asymmetries observed. A companion paper by Kammerer et al. will focus on the planets in this system using the same data. We report for the first time the presence of an extended secondary disk in thermal emission, with a curved extension bent away from the plane of the disk. This feature, which we refer to as the "cat's tail", seems to be connected with the previously reported CO clump, mid-infrared asymmetry detected in the southwest side, and the warp observed in scattered light. We present a model of this secondary disk sporadically producing dust that broadly reproduces the morphology, flux, and color of the cat's tail, as well as other features observed in the disk, and suggests the secondary disk is composed largely of porous, organic refractory dust grains.