A radially broad collisional cascade in the debris disk of γ Ophiuchi observed by JWST

2026/01/21 by Yinuo Han, Mark Wyatt, Kate Y. L. Su +13 · 1 voice
Physics and Astronomy · #astro-ph.EP

paper · pdf · doi:10.3847/1538-4357/ae6ef7

arxiv published 2026/01/21 · arxiv updated 2026/05/19

Abstract

The A1V star γ Oph, at a distance of 29.7 pc, is known from Spitzer imaging to host a debris disk with a large radial extent and from its spectral energy distribution to host inner warm dust. We imaged γ Oph with JWST/MIRI at 15 and 25.5 μm, revealing smooth and radially broad emission that extends to a radius of at least 250 au at 25.5 μm. In contrast to JWST findings of an inner small-grain component with distinct ringed structures in Fomalhaut and Vega, the mid-infrared radial profile combined with prior ALMA imaging suggests a radially broad steady-state collisional cascade with the same grain size distribution throughout the disk. This further suggests that the system is populated by a radially broad planetesimal belt from tens of au or less to well over 200 au, rather than a narrow planetesimal belt from which the observed dust is displaced to appear broad. The disk is also found to be asymmetric, which could be modelled by a stellocentric offset corresponding to a small eccentricity of ∼0.03. Such a disk eccentricity could be induced by a mildly eccentric <10 M_Jup giant planet outside 10 au, or a more eccentric companion up to stellar mass at a few au, without producing a resolvable radial gap in the disk.

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Discussions

• arxiv.org/abs/2601.15285 Gamma Ophiuchi (Bake-eo)'s debris disc is imaged by JWST, finding a broad dust disc where dust grain size is the same everywhere, implying a broad disc of planetesimals whose [bsky, 2 points, 2 comments]