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Title: THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE

Abstract

The O i 135.56 nm line is covered by NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission which studies how the solar atmosphere is energized. We study here the formation and diagnostic potential of this line by means of non-local thermodynamic equilibrium modeling employing both 1D semi-empirical and 3D radiation magnetohydrodynamic models. We study the basic formation mechanisms and derive a quintessential model atom that incorporates essential atomic physics for the formation of the O i 135.56 nm line. This atomic model has 16 levels and describes recombination cascades through highly excited levels by effective recombination rates. The ionization balance O i/O ii is set by the hydrogen ionization balance through charge exchange reactions. The emission in the O i 135.56 nm line is dominated by a recombination cascade and the line is optically thin. The Doppler shift of the maximum emission correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.0–1.5 Mm height. The total intensity of the line emission is correlated with the square of the electron density. Since the O i 135.56 nm line is optically thin, the width of the emission line is a very good diagnostic ofmore » non-thermal velocities. We conclude that the O i 135.56 nm line is an excellent probe of the middle chromosphere, and compliments other powerful chromospheric diagnostics of IRIS such as the Mg ii h and k lines and the C ii lines around 133.5 nm.« less

Authors:
;  [1]
  1. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)
Publication Date:
OSTI Identifier:
22521955
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 813; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; CHARGE-EXCHANGE REACTIONS; CHROMOSPHERE; DOPPLER EFFECT; ELECTRON DENSITY; EXCITED STATES; MAGNESIUM; MAGNETOHYDRODYNAMICS; NASA; OXYGEN; PROBES; RADIANT HEAT TRANSFER; RECOMBINATION; SUN

Citation Formats

Lin, Hsiao-Hsuan, and Carlsson, Mats. THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE. United States: N. p., 2015. Web. doi:10.1088/0004-637X/813/1/34.
Lin, Hsiao-Hsuan, & Carlsson, Mats. THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE. United States. https://doi.org/10.1088/0004-637X/813/1/34
Lin, Hsiao-Hsuan, and Carlsson, Mats. 2015. "THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE". United States. https://doi.org/10.1088/0004-637X/813/1/34.
@article{osti_22521955,
title = {THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE},
author = {Lin, Hsiao-Hsuan and Carlsson, Mats},
abstractNote = {The O i 135.56 nm line is covered by NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission which studies how the solar atmosphere is energized. We study here the formation and diagnostic potential of this line by means of non-local thermodynamic equilibrium modeling employing both 1D semi-empirical and 3D radiation magnetohydrodynamic models. We study the basic formation mechanisms and derive a quintessential model atom that incorporates essential atomic physics for the formation of the O i 135.56 nm line. This atomic model has 16 levels and describes recombination cascades through highly excited levels by effective recombination rates. The ionization balance O i/O ii is set by the hydrogen ionization balance through charge exchange reactions. The emission in the O i 135.56 nm line is dominated by a recombination cascade and the line is optically thin. The Doppler shift of the maximum emission correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.0–1.5 Mm height. The total intensity of the line emission is correlated with the square of the electron density. Since the O i 135.56 nm line is optically thin, the width of the emission line is a very good diagnostic of non-thermal velocities. We conclude that the O i 135.56 nm line is an excellent probe of the middle chromosphere, and compliments other powerful chromospheric diagnostics of IRIS such as the Mg ii h and k lines and the C ii lines around 133.5 nm.},
doi = {10.1088/0004-637X/813/1/34},
url = {https://www.osti.gov/biblio/22521955}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 813,
place = {United States},
year = {Sun Nov 01 00:00:00 EDT 2015},
month = {Sun Nov 01 00:00:00 EDT 2015}
}