[Loops] New Loops Paper

[Joan T Schmelz (jschmelz)]

Dear Colleagues,

The attached paper has finally come out in the latest issue of ApJ (691:503–515, 2009 January 20). It seems we've been working on this one for a very long time!

Regards,
Joan

ARE CORONAL LOOPS ISOTHERMAL OR MULTITHERMAL?
J.T. Schmelz, K. Nasraoui, L.A. Rightmire, J.A. Kimble, G. Del Zanna, J.W. Cirtain, E.E. DeLuca & H.E. Mason

ABSTRACT
Surprisingly few solar coronal loops have been observed simultaneously with TRACE and SOHO/Coronal
Diagnostics Spectrometer (CDS), and even fewer analyses of these loops have been conducted and published.
The SOHO Joint Observing Program 146 was designed in part to provide the simultaneous observations required
for in-depth temperature analysis of active region loops and determine whether these loops are isothermal or
multithermal. The data analyzed in this paper were taken on 2003 January 17 of AR 10250. We used TRACE
filter ratios, emission measure loci, and two methods of differential emission measure analysis to examine the
temperature structure of three different loops. TRACE and CDS observations agree that Loop 1 is isothermal with
log T = 5.85, both along the line of sight as well as along the length of the loop leg that is visible in the CDS
field of view. Loop 2 is hotter than Loop 1. It is multithermal along the line of sight, with significant emission
between 6.2 < log T < 6.4, but the loop apex region is out of the CDS field of view so it is not possible to
determine the temperature distribution as a function of the loop height. Loop 3 also appears to be multithermal,
but a blended loop that is just barely resolved with CDS may be adding cool emission to the Loop 3 intensities
and complicating our results. So, are coronal loops isothermal or multithermal? The answer appears to be yes.

Link:

http://www.iop.org/EJ/article/0004-637X/691/1/503/apj_691_1_503.pdf?request-id=f5d6ef63-7c08-4f3e-886e-4e101feb1846