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Title: THE HANLE EFFECT OF Ly{alpha} IN A MAGNETOHYDRODYNAMIC MODEL OF THE SOLAR TRANSITION REGION

Abstract

In order to understand the heating of the solar corona it is crucial to obtain empirical information on the magnetic field in its lower boundary (the transition region). To this end, we need to measure and model the linear polarization produced by scattering processes in strong UV lines, such as the hydrogen Ly{alpha} line. The interpretation of the observed Stokes profiles will require taking into account that the outer solar atmosphere is highly structured and dynamic, and that the height of the transition region may well vary from one place in the atmosphere to another. Here, we report on the Ly{alpha} scattering polarization signals we have calculated in a realistic model of an enhanced network region, resulting from a state-of-the-art radiation magnetohydrodynamic simulation. This model is characterized by spatially complex variations of the physical quantities at transition region heights. The results of our investigation lead us to emphasize that scattering processes in the upper solar chromosphere should indeed produce measurable linear polarization in Ly{alpha}. More importantly, we show that via the Hanle effect the model's magnetic field produces significant changes in the emergent Q/I and U/I profiles. Therefore, we argue that by measuring the polarization signals produced by scattering processesmore » and the Hanle effect in Ly{alpha} and contrasting them with those computed in increasingly realistic atmospheric models, we should be able to decipher the magnetic, thermal, and dynamic structure of the upper chromosphere and transition region of the Sun.« less

Authors:
 [1];  [2]; ;  [3]
  1. Astronomical Institute ASCR, Fricova 298, 251 65 Ondrejov (Czech Republic)
  2. Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
  3. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)
Publication Date:
OSTI Identifier:
22078473
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 758; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHROMOSPHERE; COMPUTERIZED SIMULATION; HEATING; HYDROGEN; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; POLARIZATION; SCATTERING; SIGNALS; SOLAR CORONA; SUN

Citation Formats

Stepan, J., Trujillo Bueno, J., Carlsson, M., and Leenaarts, J. THE HANLE EFFECT OF Ly{alpha} IN A MAGNETOHYDRODYNAMIC MODEL OF THE SOLAR TRANSITION REGION. United States: N. p., 2012. Web. doi:10.1088/2041-8205/758/2/L43.
Stepan, J., Trujillo Bueno, J., Carlsson, M., & Leenaarts, J. THE HANLE EFFECT OF Ly{alpha} IN A MAGNETOHYDRODYNAMIC MODEL OF THE SOLAR TRANSITION REGION. United States. doi:10.1088/2041-8205/758/2/L43.
Stepan, J., Trujillo Bueno, J., Carlsson, M., and Leenaarts, J. Sat . "THE HANLE EFFECT OF Ly{alpha} IN A MAGNETOHYDRODYNAMIC MODEL OF THE SOLAR TRANSITION REGION". United States. doi:10.1088/2041-8205/758/2/L43.
@article{osti_22078473,
title = {THE HANLE EFFECT OF Ly{alpha} IN A MAGNETOHYDRODYNAMIC MODEL OF THE SOLAR TRANSITION REGION},
author = {Stepan, J. and Trujillo Bueno, J. and Carlsson, M. and Leenaarts, J.},
abstractNote = {In order to understand the heating of the solar corona it is crucial to obtain empirical information on the magnetic field in its lower boundary (the transition region). To this end, we need to measure and model the linear polarization produced by scattering processes in strong UV lines, such as the hydrogen Ly{alpha} line. The interpretation of the observed Stokes profiles will require taking into account that the outer solar atmosphere is highly structured and dynamic, and that the height of the transition region may well vary from one place in the atmosphere to another. Here, we report on the Ly{alpha} scattering polarization signals we have calculated in a realistic model of an enhanced network region, resulting from a state-of-the-art radiation magnetohydrodynamic simulation. This model is characterized by spatially complex variations of the physical quantities at transition region heights. The results of our investigation lead us to emphasize that scattering processes in the upper solar chromosphere should indeed produce measurable linear polarization in Ly{alpha}. More importantly, we show that via the Hanle effect the model's magnetic field produces significant changes in the emergent Q/I and U/I profiles. Therefore, we argue that by measuring the polarization signals produced by scattering processes and the Hanle effect in Ly{alpha} and contrasting them with those computed in increasingly realistic atmospheric models, we should be able to decipher the magnetic, thermal, and dynamic structure of the upper chromosphere and transition region of the Sun.},
doi = {10.1088/2041-8205/758/2/L43},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 758,
place = {United States},
year = {2012},
month = {10}
}