Nested Dust Shells around the Wolf-Rayet Binary WR 140 observed with JWST

TL;DR

This study uses JWST observations to reveal nested dust shells around the Wolf-Rayet binary WR 140, confirming the survival of carbonaceous dust and its potential role in enriching the interstellar medium with organic compounds.

Contribution

First JWST mid-infrared observations of WR 140's dust shells, demonstrating dust survival and linking it to interstellar enrichment.

Findings

Detection of over 17 dust shells around WR 140.

Confirmation of carbonaceous dust grains surviving from the system.

Identification of spectral features associated with organic compounds.

Abstract

Massive colliding-wind binaries that host a Wolf-Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium (ISM). However, the chemical composition and survival of dust formed from such systems is not well understood. The carbon-rich WR (WC) binary WR~140 presents an ideal astrophysical laboratory for investigating these questions given its well-defined orbital period and predictable dust-formation episodes every 7.93 years around periastron passage. We present observations from our Early Release Science program (ERS1349) with the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer (MRS) and Imager that reveal the spectral and spatial signatures of nested circumstellar dust shells around WR~140. MIRI MRS spectroscopy of the second dust shell and Imager detections of over 17 shells formed throughout the past $\gtrsim130$ years confirm the survival of carbonaceous dust grains from WR~140 that are likely carriers of "unidentified infrared" (UIR)-band features at 6.4 and 7.7 $\mu$m. The observations indicate that dust-forming WC binaries can enrich the ISM with organic compounds and carbonaceous dust.