[Loops] New loop paper

[Petrus Martens]

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 tools
for rapid forward modeling of loops observed by XRT and AIA.

    Best regards,

    Piet


Scaling Laws and Temperature Profiles for Solar and Stellar Coronal 
Loops with Non-uniform Heating

P.C.H. Martens

Abstract:

The bulk of solar coronal radiative loss consists of soft X-ray emission 
from quasi-static loops at the cores of Active Regions.  In order to 
develop diagnostics for determining the heating mechanism of these loops 
from observations by coronal imaging instruments, I have developed 
analytical solutions for the temperature structure and scaling laws of 
loop strands for a wide range of heating functions, including footpoint 
heating, uniform heating, and heating concentrated at the loop apex. Key 
results are that the temperature profile depends only weakly on the 
heating distribution -- not sufficiently to be of significant diagnostic 
value --  and that the scaling laws survive for this wide range of 
heating distributions, but with the constant of proportionality in the 
RTV scaling law ($P_{0}L\, \thicksim\, T_{max}^3$) depending on the 
specific heating function.  Furthermore, quasi-static analytical 
solutions do not exist for an excessive concentration of heating near 
the loop footpoints, a result in agreement with recent numerical 
simulations.  It is demonstrated that a generalization of the solutions 
to the case of a strand with a variable diameter leads to only 
relatively small correction factors in the scaling laws and temperature 
profiles for constant diameter loop strands.  A quintet of leading 
theoretical coronal heating mechanisms is shown to be captured by the 
formalism of this paper, and the differences in thermal structure 
between them may be verified through observations.  Preliminary results 
from full numerical simulations demonstrate that, despite the 
simplifying assumptions, the analytical solutions from this paper are 
stable and accurate.



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  Piet Martens              Tel:   617-496-7769
  Center for Astrophysics   Fax:   617-496-7577
  60 Garden Street, MS 58   Cell:  617-999-0353
  Cambridge, MA 02138	   pmartens at cfa.harvard.edu
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