Dear friends,
I am very happy to announce that the Steering Committee has selected University of Cambridge as the host for Loops VIII to occur in the summer of 2015. Dr. Helen Mason will serve as SOC chair. Congratulations to Helen!
I would also like to thank the other scientists who took the time to submit a proposal to host the workshop. The SC has several excellent proposals to select from and it was a very difficult choice.
Next we are seeking to name the additional members of the SOC. According to the by-laws:
The Scientific Organizing Committee (SOC) serves for one workshop only and consists of 7 members, including the chair. The chair of the previous workshop is an ex officio member. The remaining 5 members are elected by the Steering Committee from a slate of candidates nominated by the SC with informal input from the loops community. It is highly desirable that the SOC contain a mix of observers and theorists. SOC members may serve multiple times. SC members may serve on the SOC contemporaneously.
If you are interested in serving on the SOC or would like to suggest someone else, please email me directly at amy.winebarger@nasa.gov before Wednesday, August 20. Note if you “reply” to this message, it will go to the entire list.
Best wishes, Amy
-- Dr. Amy R. Winebarger NASA Marshall Space Flight Center ZP 13 Huntsville, AL 35812 Voice : 256-961-7509 Fax : 256-961-7216
Aschwanden,M.J. . 2015, ApJL ... (revised, 2015 Apr 2) URL1="http://www.lmsal.com/~aschwand/eprints/2015_iris.pdf" Magnetic energy dissipation during the 2014 Mar 29 flare: Consistent measurements in the transition region and corona with IRIS and AIA/SDO
____________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ____________________________________
Thank you Markus for the preprint. Looking at your most important Fig. 3, you give the impression that MORE free energy is available in the corona AFTER the peak of the flare (GOES HXR, SXR emissions, etc) than before. Is not exactly the opposite of what we would wait following your Introductory presentation of the topic and even the title of the paper? Or did I miss something fundamental? Best, S.
Le 13/04/2015 21:06, Markus J. Aschwanden a écrit :
Aschwanden,M.J. . 2015, ApJL ... (revised, 2015 Apr 2) URL1="http://www.lmsal.com/~aschwand/eprints/2015_iris.pdf" http://www.lmsal.com/%7Easchwand/eprints/2015_iris.pdf Magnetic energy dissipation during the 2014 Mar 29 flare: Consistent measurements in the transition region and corona with IRIS and AIA/SDO
Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ http://www.lmsal.com/%7Easchwand/ e-mail: aschwanden@lmsal.com mailto:aschwanden@lmsal.com ____________________________________
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That’s how it appears to me too. I’d add that the localization of the free energy is a difficult subject, and it may be misleading just to identify it with the B^2/8pi excess. This is because the realization of the free energy, i.e. its actual definition, depends on the nature of the instability that releases it. Understanding this requires understanding the boundary conditions, so it must be a higher-order theoretical matter.
Hugh
On Apr 14, 2015, at 8:42 AM, Serge Koutchmy koutchmy@iap.fr wrote:
Thank you Markus for the preprint. Looking at your most important Fig. 3, you give the impression that MORE free energy is available in the corona AFTER the peak of the flare (GOES HXR, SXR emissions, etc) than before. Is not exactly the opposite of what we would wait following your Introductory presentation of the topic and even the title of the paper? Or did I miss something fundamental? Best, S.
Le 13/04/2015 21:06, Markus J. Aschwanden a écrit :
Aschwanden,M.J. . 2015, ApJL ... (revised, 2015 Apr 2) URL1="http://www.lmsal.com/~aschwand/eprints/2015_iris.pdf" Magnetic energy dissipation during the 2014 Mar 29 flare: Consistent measurements in the transition region and corona with IRIS and AIA/SDO
Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ____________________________________
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Dear Serge and Hugh,
Thanks for your feedback. You are correct that it appears that there is more free energy available during the flare duration than before or after. However, a similar behavior appears in all flares, as you can see in the analysis of the free energy in some 200 flares analyzed from HMI and AIA (see Aschwanden, Xu, and Jing 2014, ApJ 797:50). This apparently counter-intuitive behavior has been interpreted as a “coronal illumination effect” (see Fig.3 in the quoted paper above). In short, most of the highly twisted helical flare loops that carry non-potential magnetic energy are invisible or undetectable before the start of the flare, but become visible once they become filled up with heated plasma by the chromospheric evaporation process that usually occurs in flares. So, it is not a contra- diction, but just an observational problem. It is similar to the missing mass problem in the universe: We detect only 4% luminous mass, but when you add up all the dark matter and neutrinos you get to a much more massive universe that may even be closed/ And nobody calls the missing mass problem as contradictory, it’s just an observational problem.
Regarding Hugh’s comment, the NLFFF model that has been used to calculate the free energy is based on an analytical solution of the force-free field in terms of vertical currents that introduce a helical twist (Aschwanden 2013, Solar Phys. 287, 323). It is only an approximation, but it should give the first-order non-potential field pretty accurately. There is some consistency with standard NLFFF models, or at least some correlation (e.g., Wiegelmann code). The boundary conditions have been discussed in great detail in a NLFFF comparison paper (DeRosa et al. 2009). The biggest problem with standard NLFFF codes is that they extrapolate from a not force-free boundary. In contrast, the analytical NLFFF model that fits the geometry of coronal loops circumvents this problem and thus yields complementary information. If you wish I can give your more references on this “high-order theoretical matter”.
Thanks for the comments, Best regards,
Markus
____________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ____________________________________
On Apr 14, 2015, at 5:53 AM, Hugh Hudson hhudson@ssl.berkeley.edu wrote:
That’s how it appears to me too. I’d add that the localization of the free energy is a difficult subject, and it may be misleading just to identify it with the B^2/8pi excess. This is because the realization of the free energy, i.e. its actual definition, depends on the nature of the instability that releases it. Understanding this requires understanding the boundary conditions, so it must be a higher-order theoretical matter.
Hugh
On Apr 14, 2015, at 8:42 AM, Serge Koutchmy koutchmy@iap.fr wrote:
Thank you Markus for the preprint. Looking at your most important Fig. 3, you give the impression that MORE free energy is available in the corona AFTER the peak of the flare (GOES HXR, SXR emissions, etc) than before. Is not exactly the opposite of what we would wait following your Introductory presentation of the topic and even the title of the paper? Or did I miss something fundamental? Best, S.
Le 13/04/2015 21:06, Markus J. Aschwanden a écrit :
Aschwanden,M.J. . 2015, ApJL ... (revised, 2015 Apr 2) URL1="http://www.lmsal.com/~aschwand/eprints/2015_iris.pdf" Magnetic energy dissipation during the 2014 Mar 29 flare: Consistent measurements in the transition region and corona with IRIS and AIA/SDO
Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ____________________________________
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Message from Jaroslav Dudik:
Dear all,
our paper on diagnostics of the non-Maxwellian kappa-distributions in a transient coronal loop observed by SDO/AIA and Hinode/EIS has been accepted for publication in The Astrophysical Journal. Please find the abstract and an ArXiV link below.
Title: Imaging and Spectroscopic Observations of a Transient Coronal Loop: Evidence for the Non-Maxwellian Kappa-Distributions
Authors: Jaroslav Dudik, Simon Mackovjak, Elena Dzifcakova, Giulio Del Zanna, David R. Williams, Marian Karlicky, Helen E. Mason, Juraj Lorincik, Pavel Kotrc, Frantisek Farnik, Alena Zemanova
Abstract: We report on the SDO/AIA and Hinode/EIS observations of a transient coronal loop. The loop brightens up in the same location after the disappearance of an arcade formed during a B8.9-class microflare three hours earlier. EIS captures this loop during its brightening phase as observed in most of the AIA filters. We use the AIA data to study the evolution of the loop, as well as to perform the DEM diagnostics as a function of kappa. Fe XI--XIII lines observed by EIS are used to perform the diagnostics of electron density and subsequently the diagnostics of kappa. Using ratios involving the Fe XI 257.772A selfblend, we diagnose kappa < 2, i.e., an extremely non-Maxwellian distribution. Using the predicted Fe line intensities derived from the DEMs as a function of kappa, we show that, with decreasing κ, all combinations of ratios of line intensities converge to the observed values, confirming the diagnosed kappa ≲ 2. These results represent the first positive diagnostics of kappa-distributions in the solar corona despite the limitations imposed by calibration uncertainties.
My best regards, Jaro
--------------------
Dear All,
Can we determine the 3D geometry of coronal loops blindly ?
Cheers, Markus
Aschwanden,M.J., Schrijver, C.J., and Malanushenko, A. 2015, Solar Physics (accepted, 2015 June 15), in press URL1="http://www.lmsal.com/~aschwand/eprints/2015_blind.pdf" Blind stereoscopy of coronal magnetic fields
ArXive preprint:
http://arxiv.org/abs/1506.04713
____________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ____________________________________
Aschwanden,M.J., Boerner, P., Caspi, A., McTiernan, J.M., Ryan, D., and Warren, H.P. 2015, Solar Physics ... (in press) URL1="http://www.lmsal.com/~aschwand/eprints/2015_dem.pdf" Benchmark Test of Differential Emission Measure Codes and Multi-Thermal Energies in Solar Active Regions
____________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center A021S, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com ___________________________________
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