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Title: A three-dimensional view of the thermal structure in a super-penumbral canopy

We investigate the three-dimensional (3D) thermal topology in a super-penumbral canopy of an active region (AR). We derive temperature stratifications in the AR by an inversion of the Ca II IR line at 854.2 nm, assuming local thermal equilibrium. We find that about half of the radially oriented fibrils in the super-penumbral canopy form short, low-lying (h < 1 Mm) loops in the 3D temperature cube. These closed loops connect from bright grains in or close to the penumbra to the photosphere a few Mms away from the sunspot. The other half of the fibrils monotonically rise with distance from the sunspot. Many of the fibrils show a central dark core and two lateral brightenings in line-core intensity images. The corresponding velocity image shows fibrils that are as wide as the fibrils seen in intensity without a lateral substructure. Additionally, we study a feature from a different class of structures without prominent mass flows. Its 3D topology is formed by two parallel, closed loops that connect patches of opposite polarity. We present evidence that the inverse Evershed flow into the sunspot in the lower chromosphere is the consequence of siphon flows along short loops that connect photospheric foot points. Themore » dark-cored structure of the chromospheric fibrils cannot have a convective origin because of their location above regular granulation. The dark core most likely results from an opacity difference between the central axis and the lateral edges caused by the significant flow speed along the fibrils.« less
Authors:
 [1] ;  [2] ;  [3]
  1. National Solar Observatory (NSO), 3010 Coronal Loop, Sunspot, NM 88349 (United States)
  2. Department of Physics and Astronomy, California State University, Northridge (CSUN), CA 91330-8268 (United States)
  3. Kiepenheuer Institut f├╝r Sonnenphysik (KIS), Sch├Âneckstrasse 6, D-79104 Freiburg (Germany)
Publication Date:
OSTI Identifier:
22356539
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; 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; DATA ANALYSIS; MASS; METHYL METHANESULFONATE; OPACITY; PHOTOSPHERE; STRATIFICATION; SUN; SUNSPOTS; THERMAL EQUILIBRIUM; THREE-DIMENSIONAL CALCULATIONS; TOPOLOGY; VELOCITY