URL1="http://www.lmsal.com/~aschwand/eprints/2008_hydroapprox.pdf"
Analytical approximations in explicit form for the hydrodynamic evolution of heated and cooling coronal loops
Folks,I submitted the following paper to ApJ and put a copy on Astro-Ph:Article-id: 0804.2241. Its main purpose was to develop the toolsfor rapid forward modeling of loops observed by XRT and AIA.Best regards,PietScaling Laws and Temperature Profiles for Solar and Stellar CoronalLoops with Non-uniform HeatingP.C.H. MartensAbstract:The bulk of solar coronal radiative loss consists of soft X-ray emissionfrom quasi-static loops at the cores of Active Regions. In order todevelop diagnostics for determining the heating mechanism of these loopsfrom observations by coronal imaging instruments, I have developedanalytical solutions for the temperature structure and scaling laws ofloop strands for a wide range of heating functions, including footpointheating, uniform heating, and heating concentrated at the loop apex. Keyresults are that the temperature profile depends only weakly on theheating distribution -- not sufficiently to be of significant diagnosticvalue -- and that the scaling laws survive for this wide range ofheating distributions, but with the constant of proportionality in theRTV scaling law ($P_{0}L\, \thicksim\, T_{max}^3$) depending on thespecific heating function. Furthermore, quasi-static analyticalsolutions do not exist for an excessive concentration of heating nearthe loop footpoints, a result in agreement with recent numericalsimulations. It is demonstrated that a generalization of the solutionsto the case of a strand with a variable diameter leads to onlyrelatively small correction factors in the scaling laws and temperatureprofiles for constant diameter loop strands. A quintet of leadingtheoretical coronal heating mechanisms is shown to be captured by theformalism of this paper, and the differences in thermal structurebetween them may be verified through observations. Preliminary resultsfrom full numerical simulations demonstrate that, despite thesimplifying assumptions, the analytical solutions from this paper arestable and accurate.--------------------------------------------------------------------Piet Martens Tel: 617-496-7769Center for Astrophysics Fax: 617-496-757760 Garden Street, MS 58 Cell: 617-999-0353--------------------------------------------------------------------_______________________________________________Loops mailing list