The Effect of a Solar Wind Blast Wave on the Chromosphere.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Effect of a Solar Wind Blast Wave on the Chromosphere. Wentzel, Donat G. ; Solinger, Alan B. Abstract The enhanced solar wind following some solar flares is probably caused by coronal heating. The energy involved in the enhanced wind suggests that flare-induced coronal heating occurs over an area extending far beyond the flare area. The resulting disturbance of the underlying nonflaring chromosphere is computed on the assumption that the corona is heated suddenly. In this case, a shock moves downward from the heated region. The increase in the undisturbed chromospheric density ahead of the shock (p) tends to weaken the shock. In addition, magnetic fields may act as a guide for the shock. An increase in field strength along the shock's path constricts the area of the shock front (A) and tends to strengthen the shock. Both effects can be evaluated analytically, using Whitham's theory for shock propagation in inhomogeneous media (J. Fluid Mech. 4, 337, 1958), if both the shock and the chromosphere are considered to be isothermal. The change in Mach number (M) with p and A is given by 1 1 2 dp dA 1+ +-+ dM+-+-= 0. M2 M M-1 p A For plane stratification or vertical magnetic fields (dA =0), the shock penetrates gas increasing in density by one to two orders of magnitude before attenuation becomes significant. Its effect may relate to the flare nimbus and to the disappearance of stria- tion patterns. The strength of a shock entering the field of a sunspot (dA/dp<0) is attenuated much less. Flaring over sunspot umbrae may be initiated by such a shock. Publication: The Astronomical Journal Pub Date: February 1966 DOI: 10.1086/110121 Bibcode: 1966AJ.....71R.402W full text sources ADS |