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SETI Study: Stellar Space Weather Can Blur Alien Radio Signals, Masking Narrowband Technosignatures

A peer-reviewed model, calibrated with spacecraft transmissions, finds stellar plasma can widen signals by tens of hertz, prompting a revamp of search strategies.

Overview

  • Published March 5 in the Astrophysical Journal, the study quantifies how plasma near stars broadens radio transmissions enough to push legitimate technosignatures below today’s narrowband detection thresholds.
  • Using distortions measured from human spacecraft such as Mariner, Pioneer, Helios, Viking, Mars Express, Venus Express and Rosetta, the authors extrapolate a framework for other stellar systems.
  • The analysis estimates broadening commonly reaches 10–100 Hz and can surge during stellar storms, with examples such as a 100 megahertz signal widening by about 100 hertz.
  • Active M-dwarf stars, which make up roughly three-quarters of the Milky Way’s population, are flagged as especially likely to smear signals, challenging target priorities that emphasize these stars.
  • No technosignature is reported; instead, the work urges SETI pipelines to stay sensitive to broader, fuzzier signals and to revisit long-standing assumptions that prioritize ultra-narrow beacons.