The Physical Origin of Periodic Density Structures in the Solar Wind: Coronal Streamers as Magnetohydrodynamic Resonators

TL;DR

This paper proposes that coronal streamers act as magnetohydrodynamic resonators, explaining the observed periodic density structures in the solar wind through resonant wave phenomena and reconnection processes.

Contribution

It introduces a novel physical model identifying coronal streamers as natural MHD resonators that produce observed periodic density structures in the solar wind.

Findings

Coronal streamers have harmonic periods matching observed PDS.

Resonant slow magnetoacoustic waves create density enhancements.

Reconnection at streamer cusps releases plasma blobs at resonant periods.

Abstract

We present a comprehensive physical model explaining the origin of Periodic Density Structures (PDS) observed in white-light coronagraphs with characteristic periods of approximately 45, 80, and 120 minutes. Through systematic investigation of potential resonant cavities in the solar atmosphere, we demonstrate that traditional large-scale cavities yield fundamentally incompatible periods: photosphere-transition region (3.3 minutes), transition region-sonic point (10.3 hours), and transition region-heliopause (7.7 years). We establish that coronal streamers act as natural magnetohydrodynamic resonators, with calculated harmonic periods of 122, 61, and 41 minutes that precisely match observations. The physical mechanism involves slow magnetoacoustic standing waves that create periodic density enhancements through wave compression, with the streamer resonator having quality factor Q ~ 10-100, enabling natural amplification of broadband coronal noise. At streamer cusps, these density enhancements trigger magnetic reconnection, releasing plasma blobs into the solar wind at resonant periods. The model provides complete energy budget calculations, wave amplitude estimates, and explains all key observational features including spatial localization, period coherence, and the relationship between remote sensing and in situ measurements. This work establishes streamer resonators as fundamental structures shaping solar wind variability and provides a new framework for understanding the emergence of coherent structures in turbulent astrophysical plasmas.