[Loops] coronal heating, emission, and loops

[Klimchuk, James A. (GSFC-6710)]

Dear friends,

You might be interested in this recently accepted paper entitled "Observational Signatures of Coronal Heating in MHD Models Without Radiation or a Lower Atmosphere" by me, Kalman Knizhnik, and Vadim Uritsky. It presents a method of estimating the radiation expected from such models and applies it to one of our previously published simulations. We offer an explanation for the origin of both the diffuse component of the corona and observationally distinct coronal loops.

https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Farxiv.org%2Fabs%2F2211.00104&data=05%7C01%7CJames.A.Klimchuk%40nasa.gov%7C35fdec5b20bd4f773f0a08dabc688880%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C638029454391784356%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=%2B2KfgAMQaxbKjb6b%2BxGegkOcT%2Fs6VYkYa3fRw%2F%2Bioes%3D&reserved=0

Abstract:

It is extremely difficult to simulate the details of coronal heating and also make meaningful predictions of the emitted radiation. Thus, testing realistic models with observations is a major challenge. Observational signatures of coronal heating depend crucially on radiation, thermal conduction, and the exchange of mass and energy with the transition region and chromosphere below. Many magnetohydrodynamic simulation studies do not include these effects, opting instead to devote computational resources to the magnetic aspects of the problem. We have developed a simple method of accounting approximately for the missing effects. It is applied to the simulation output post facto and therefore may be a valuable tool for many studies. We have used it to predict the emission from a model corona that is driven by vortical boundary motions meant to represent photospheric convection. We find that individual magnetic strands experience short-term brightenings, both scattered throughout the computational volume and in localized clusters. The former may explain the diffuse component of the observed corona, while the latter may explain bright coronal loops. Several observed properties of loops are reproduced reasonably well:  width, lifetime, and quasi-circular cross-section (aspect ratio not large). Our results lend support to the idea that loops are multi-stranded structures heated by "storms" of nanoflares.

Best wishes,
Jim


********************************************************************************
James A. Klimchuk (he/him)
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD  20771
USA

Phone:  1-301-286-9060<tel:%28301%29%20286-9060>
Fax:      1-301-286-7194<tel:%28301%29%20286-7194>
E-mail:  James.A.Klimchuk at nasa.gov<mailto:James.A.Klimchuk at nasa.gov>
Homepage:  http://science.gsfc.nasa.gov/sed/bio/james.a.klimchuk<http://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844>

No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.

********************************************************************************

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://solar.physics.montana.edu/pipermail/loops/attachments/20221102/2b84b127/attachment.htm>