The first white dwarf debris disc observed by JWST

Abstract

ABSTRACT This letter reports the first JWST spectroscopy of a white dwarf debris disc, giving a preliminary assessment of the salient features, and recommendations for future observations. The polluted and dusty star WD 0145+234 experienced a major collisional event in its circumstellar disc in 2018, accompanied by an infrared outburst, and subsequently a gradual decrease in thermal emission. Time-series NIRSpec observations demonstrate that the circumstellar disc is returning to a quiescent state with a T ≈ 1000 K infrared excess similar to the bulk of known dusty white dwarfs. MIRI spectroscopy reveals a 9–12 $\mu$m solid-state emission feature consistent with silicate minerals as seen in debris discs observed with Spitzer. The strength and morphology of the silicate feature appear unchanged relative to the continuum in spectra taken over a year apart, consistent with steady-state collisional evolution of the circumstellar debris. A tentative emission feature around 7 $\mu$m may be due to carbonates, and if confirmed would indicate aqueous alteration in the parent body.