One- vs. Two-Shock Heliosphere: Constraining Models with GHRS LyA Spectra toward alpha Cen
Abstract
Redshifted L absorption toward Cen has been interpreted by Linsky & Wood (1996) and Frisch et al. (1996) as evidence for decelerated interstellar hydrogen piled up on the upstream side of the heliosphere. We utilize newly developed two-dimensional multi-fluid models of the solar wind interaction with the ISM to corroborate this interpretation by synthesizing the L absorption profile predicted for this ``hydrogen wall''. Both subsonic and supersonic inflow into the heliosphere are considered, corresponding to one-shock and two-shock global morphologies, respectively. It is found that these two extremes give observably different redward absorption characteristics in the L profiles, and our preliminary conclusion is that the L profiles seen toward Cen favor a barely subsonic model (Mach number 0.9). For such a model to hold, additional interstellar pressure terms, such as cosmic ray or magnetic pressures, must contribute. To make this conclusion more certain, an extended model-parameter survey is required, coupled with L data along other lines of sight.
Cite
@article{arxiv.astro-ph/9706043,
title = {One- vs. Two-Shock Heliosphere: Constraining Models with GHRS LyA Spectra toward alpha Cen},
author = {K. G. Gayley and G. P. Zank and H. L. Pauls and P. C. Frisch and D. E. Welty},
journal= {arXiv preprint arXiv:astro-ph/9706043},
year = {2007}
}