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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Dear Loop Lovers,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>The attached paper on AIA multithermal loop analysis has just been published in ApJ Letters. Comments welcome!<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>ATMOSPHERIC IMAGING ASSEMBLY MULTITHERMAL LOOP ANALYSIS: FIRST RESULTS<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>by<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>J. T. Schmelz, J. A. Kimble, B. S. Jenkins, B. T. Worley, D. J. Anderson, S. Pathak, and S. H. Saar</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:blue'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><i><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'><o:p> </o:p></span></i></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>ABSTRACT<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>The Atmospheric Imaging Assembly (AIA) on board the <i>Solar Dynamics Observatory </i>has state-of-the-art spatial<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>resolution and shows the most detailed images of coronal loops ever observed. The series of coronal filters<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>peak at different temperatures, which span the range of active regions. These features represent a significant<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>improvement over earlier coronal imagers and make AIA ideal for multithermal analysis. Here, we targeted<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>a 171 Å coronal loop in AR 11092 observed by AIA on 2010 August 3. Isothermal analysis using the<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>171-to-193 ratio gave a temperature of log <i>T </i>≈ 6.1, similar to the results of Extreme ultraviolet Imaging<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>Spectrograph (EIT) and <i>TRACE</i>. Differential emission measure analysis, however, showed that the plasma was<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>multithermal, not isothermal, with the bulk of the emission measure at log <i>T > </i>6.1. The result from the isothermal<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>analysis, which is the average of the true plasma distribution weighted by the instrument response functions,<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>appears to be deceptively low. These results have potentially serious implications: EIT and <i>TRACE </i>results,<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>which use the same isothermal method, show substantially smaller temperature gradients than predicted by<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>standard models for loops in hydrodynamic equilibrium and have been used as strong evidence in support of<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>footpoint heating models. These implications may have to be re-examined in the wake of new results from AIA.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>Joan</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p></div></body></html>