EFFECTS OF UNRESOLVED MAGNETIC FIELD ON Fe I 617.3 AND 630.2 nm LINE SHAPES

The contribution of the quiet Sun to solar irradiance variability, either due to changes of the solar effective temperature or to the presence of unresolved magnetic field, is still poorly understood. In this study we investigate spectral line diagnostics that are sensitive to both temperature varia...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2013-02, Vol.763 (2), p.1-9
Main Authors: Criscuoli, S, Ermolli, I, UITENBROEK, H, Giorgi, F
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
Density
Integrated circuits
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETISM
Mathematical models
NOAA
PHOTOSPHERE
RADIANT FLUX DENSITY
RADIANT HEAT TRANSFER
Solar atmosphere
SPECTROMETERS
SUN
SURFACES
TELESCOPES
VARIATIONS
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The contribution of the quiet Sun to solar irradiance variability, either due to changes of the solar effective temperature or to the presence of unresolved magnetic field, is still poorly understood. In this study we investigate spectral line diagnostics that are sensitive to both temperature variations and the presence of small-scale unresolved magnetic features in these areas of the solar atmosphere. Specifically, we study the dependence on the magnetic flux density of three parameters describing the shape of two magnetically sensitive Fe I lines, at 630.2 nm and 617.3 nm, namely the line core intensity (IC), the FWHM, and the equivalent width (EQW). To this end we analyze observations of active region NOAA 11172, acquired with Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope, as well as results from numerical synthesis. Our results show that IC is sensitive to both temperature and magnetic flux density variations, FWHM is mostly affected by magnetic field changes, and EQW is mostly sensitive to temperature. Variations of a few percent of the measured line parameters are found in observational data that were spatially degraded to represent quiet-Sun, disk-center, medium-resolution observations. It is therefore possible to disentangle magnetic from pure thermodynamic effects by the comparison of temporal variations of the EQW and the FWHM of either of the two Fe I lines.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/763/2/144