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Early Interferometric Images Recast Novae as Multi-Stage, Directional Eruptions

CHARA observations within days link ejecta geometry to shock-driven gamma rays seen by Fermi.

Overview

  • The peer-reviewed study in Nature Astronomy reports the first spatially resolved views of the 2021 novae V1674 Herculis and V1405 Cassiopeiae captured within days using the CHARA Array.
  • V1674 Herculis showed two perpendicular outflows just 2–3 days after discovery, with their interaction coinciding with Fermi gamma rays that indicate shock formation.
  • V1405 Cassiopeiae delayed the bulk ejection of its envelope for more than 50 days before a late release produced fresh shocks and renewed high-energy emission.
  • Spectroscopic data from major facilities including Gemini tracked evolving gas signatures that matched the structures seen in the images, reinforcing the flow-and-collision picture.
  • The results overturn the simple single-impulse model for nova mass loss and sharpen models of envelope ejection and particle acceleration, with an arXiv preprint posted December 8.