Overview

• Observations of X-ray binaries GX 340+0 and 4U 1630–472 provided bright backlights for the Resolve spectrometer to detect sulfur absorption in both its gaseous and solid forms
• Spectral signatures point to iron-sulfur minerals such as pyrrhotite, troilite and pyrite accounting for the solid-phase sulfur in dense molecular clouds
• These direct X-ray measurements surpass previous ultraviolet and Chandra studies by confirming sulfur’s solid phase where stars and planets take shape
• XRISM, led by JAXA with NASA and ESA contributions, employs the Resolve microcalorimeter developed by NASA and JAXA for unprecedented chemical sensitivity
• The team is conducting additional XRISM observations to refine models of sulfur’s role in galactic chemical cycles and cosmic dust formation