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Title: PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS

Abstract

Recent observations from the Interface Region Imaging Spectrograph ( IRIS ) have discovered a new class of numerous low-lying dynamic loop structures, and it has been argued that they are the long-postulated unresolved fine structures (UFSs) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of the properties of a sample of 108 UFSs (intensities, lengths, widths, lifetimes) with one-dimensional non-equilibrium ionization simulations, using the HYDRAD hydrodynamic model to examine whether the UFSs are now truly spatially resolved in the sense of being individual structures rather than being composed of multiple magnetic threads. We find that a simulation of an impulsively heated single strand can reproduce most of the observed properties, suggesting that the UFSs may be resolved, and the distribution of UFS widths implies that they are structured on a spatial scale of 133 km on average. Spatial scales of a few hundred kilometers appear to be typical for a range of chromospheric and coronal structures, and we conjecture that this could be an important clue for understanding the coronal heating process.

Authors:
 [1]; ;  [2]
  1. College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
  2. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
Publication Date:
OSTI Identifier:
22654263
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 826; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHROMOSPHERE; DISTRIBUTION; EMISSION; EQUILIBRIUM; FINE STRUCTURE; HYDRODYNAMIC MODEL; HYDRODYNAMICS; INTERFACES; IONIZATION; LIFETIME; ONE-DIMENSIONAL CALCULATIONS; SIMULATION; SUN; ULTRAVIOLET RADIATION

Citation Formats

Brooks, David H., Reep, Jeffrey W., and Warren, Harry P.. PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS. United States: N. p., 2016. Web. doi:10.3847/2041-8205/826/2/L18.
Brooks, David H., Reep, Jeffrey W., & Warren, Harry P.. PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS. United States. doi:10.3847/2041-8205/826/2/L18.
Brooks, David H., Reep, Jeffrey W., and Warren, Harry P.. 2016. "PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS". United States. doi:10.3847/2041-8205/826/2/L18.
@article{osti_22654263,
title = {PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS},
author = {Brooks, David H. and Reep, Jeffrey W. and Warren, Harry P.},
abstractNote = {Recent observations from the Interface Region Imaging Spectrograph ( IRIS ) have discovered a new class of numerous low-lying dynamic loop structures, and it has been argued that they are the long-postulated unresolved fine structures (UFSs) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of the properties of a sample of 108 UFSs (intensities, lengths, widths, lifetimes) with one-dimensional non-equilibrium ionization simulations, using the HYDRAD hydrodynamic model to examine whether the UFSs are now truly spatially resolved in the sense of being individual structures rather than being composed of multiple magnetic threads. We find that a simulation of an impulsively heated single strand can reproduce most of the observed properties, suggesting that the UFSs may be resolved, and the distribution of UFS widths implies that they are structured on a spatial scale of 133 km on average. Spatial scales of a few hundred kilometers appear to be typical for a range of chromospheric and coronal structures, and we conjecture that this could be an important clue for understanding the coronal heating process.},
doi = {10.3847/2041-8205/826/2/L18},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 826,
place = {United States},
year = 2016,
month = 8
}
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