Type: Journal Article
Venue: The Astrophysical Journal
Edisher Kh. Kaghasvili, Richard A. Quinn and Joseph V. Hollweg 2009: Driven Waves as a Diagnostic Tool in the Solar Corona. AstroPhys J., 703, 1318. Doi:10.1088/0004-637X/703/2/1318
Resource Link: http://iopscience.iop.org/0004-637X/703/2/1318/
Detecting the signature of Alfvén waves in the solar atmosphere remains an observational challenge. At the same time, it could also be an important key to gaining critical understanding of the solar wind and especially of the near-Earth space weather formation. Here, we investigate the plausibility of using inhomogeneous flow-driven compressional fluctuations as a diagnostics tool for Alfvén waves in the solar corona. The nature of the fluctuations driven by transverse Alfvén waves in inhomogeneous flows was recently investigated by Kaghashvili et al., and analytical solutions that accurately link driven waves to the Alfvénic driver were found. The novelty of this mechanism is that the analysis of the detected compressional fluctuations can provide a clue about the Alfvén waves that are otherwise difficult to detect. We review this physical process in a low-β approximation relevant to solar coronal conditions and outline basic reasons why it can be one of the major processes that comes about as outflowing plasma emerges from divergent coronal holes. After establishing a quantitative link, we consider an example with coronal hole plasma parameters similar to the ones reported recently where evidence for Alfvén waves in solar X-ray jets was discussed. We show how this diagnostics tool can be used to analyze the detected intensity fluctuations.