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JWST and ALMA Pin Down Nano-Dominated Dust Around Wolf–Rayet Binary WR 112

ALMA’s lack of millimeter emission alongside JWST’s infrared spirals provided the decisive clue to the grains’ true sizes.

Overview

  • The peer-reviewed study in The Astrophysical Journal, led by Donglin Wu, combines spatially resolved JWST and ALMA data to resolve decades of conflicting dust measurements.
  • Modeling of the spectral energy distribution indicates a bimodal grain-size distribution dominated by nanometer-scale carbon grains with a secondary population near 0.1 micrometer.
  • JWST revealed bright mid-infrared spiral dust arcs, while ALMA detected no corresponding millimeter emission, implying a scarcity of larger, millimeter-emitting grains.
  • The authors propose radiative torque disruption and radiation-driven sublimation as likely processes that preferentially remove intermediate-sized grains, a hypothesis that remains under investigation.
  • WR 112 ejects roughly three lunar masses of carbon dust per year, sharpening estimates of how massive binaries seed the galaxy and raising questions about grain survival and system-to-system variability.