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Title: Dynamic properties along the neutral line of a delta spot inferred from high-resolution observations

Delta (δ) spots are complex magnetic configurations of sunspots characterized by umbrae of opposite polarity sharing a common penumbra. In order to investigate the fine structure of the region separating the two magnetic polarities of a δ spot, we studied the morphology, the magnetic configuration, and the velocity field in such a region using observations of active region (AR) NOAA 11267 obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on 2011 August 6. The analysis of CRISP data shows upflows and downflows of ∼ ± 3 km s{sup –1} in proximity of the δ spot polarity inversion line (PIL), and horizontal motions along the PIL of the order of ∼1 km s{sup –1}. The results obtained from the SIR inversion of CRISP data also indicate that the transverse magnetic field in the brighter region separating the two opposite magnetic polarities of the δ spot is tilted about ∼45° with respect to the PIL. Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations confirm the presence of motions of ∼ ± 3 km s{sup –1} in proximity of the PIL, which were observed to last 15 hr. From the data analyzed, we conclude that the steady, persistent, and subsonicmore » motions observed along the δ spot PIL can be interpreted as being due to Evershed flows occurring in the penumbral filaments that show a curved, wrapped configuration. The fluting of the penumbral filaments and their bending, continuously increased by the approaching motion of the negative umbra toward the positive one, give rise to the complex line-of-sight velocity maps that we observed.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Dipartimento di Fisica e Astronomia-Sezione Astrofisica, Università di Catania, via S. Sofia 78, I-95123 Catania (Italy)
  2. INAF-Osservatorio Astrofisico di Catania, via S. Sofia 78, I-95123 Catania (Italy)
  3. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)
  4. Institute for Solar Physics, Department of Astronomy, Stockholm University, Albanova University Center, SE-10691 Stockholm (Sweden)
  5. INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio Catone (Italy)
  6. NSO-National Solar Observatory, Sacramento Peak Box 62, Sunspot, NM 88349 (United States)
Publication Date:
OSTI Identifier:
22365651
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; 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; FINE STRUCTURE; MAGNETIC FIELDS; MAPS; PHOTOSPHERE; RESOLUTION; SUN; SUNSPOTS; TELESCOPES; VELOCITY