E-Print Archive

There are 4488 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Thomson scattering in the lower corona in the presence of sunspots View all abstracts by submitter

Pascal Saint-Hilaire   Submitted: 2021-10-12 20:54

Polarized scattered light from low (few tens of Mm altitudes) coronal transients has been recently reported in SDO/HMI observations. In a classic paper, Minnaert (1930) provided an analytic theory of polarization via electron scattering in the corona. This work assumed axisymmetric input from the photosphere with a single-parameter limb-darkening function. This diagnostic has recently been used to estimate free electron number and mass of HMI transients near the solar limb, but it applies equally well to any coronal material, at any height. Here we extend this work numerically to incorporate sunspots, which can strongly effect the polarization properties of the scattered light in the low corona. Sunspot effects are explored first for axisymmetric model cases, and then applied to the full description of two sunspot groups as observed by HMI. We find that, 1) As previously reported by Minnaert, limb darkening has a strong influence, usually increasing the level of linear polarization tangential to the limb; 2) Unsurprisingly, the effects of the sunspot generally increase at the lower scatterer altitudes, the larger the sunspot is, and the closer to their center the scatterer subpoint is; 3) Assuming the Stokes Q>0 basis to be tangential to the limb, sunspots typically decrease the Stokes Q/I polarization and the perceived electron densities below the spotless case, sometimes dramatically; 4) Typically, a sizeable non-zero Stokes U/I polarization component will appear when a sunspotís influence becomes non-negligible. However, that is not true in rare cases of extreme symmetry (e.g. scattering mass at the center of an axisymetric sunspot). The tools developed here are generally applicable to an arbitrary image input.

Authors: Pascal Saint-Hilaire, Juan-Carlos Martinez Oliveros, Hugh S. Hudson
Projects: None

Publication Status: Accepted in ApJ
Last Modified: 2021-10-13 13:06
Go to main E-Print page  Common origin of quasi-periodic pulsations in microwave and decimetric solar radio bursts  The Spatial and Temporal Variations of Turbulence in a Solar Flare  Edit Entry  Download Preprint  Delete Entry 

Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
The relativistic solar particle event on 28 October 2021: Evidence of particle acceleration within and escape from the solar corona
Statistical Analysis of Stellar Flares from the First Three Years of TESS Observations
Interface Region Imaging Spectrograph (IRIS) Observations of the Fractal Dimension in the Solar Atmosphere
Clusters of Solar Radio Spikes Modulated by Quasi-Periodic Pulsations in a Confined Flare
Dynamic Property and Magnetic Nonpotentiality of Two Types of Confined Solar Flares
Terrestrial volcanic eruptions and their possible links with solar activity
Transition to turbulence in nonuniform coronal loops driven by torsional Alfvén waves. II. Extended analysis and effect of magnetic twist
Bayesian approach for modeling solar active region global magnetic parameters
Where is the base of the Transition Region? Evidence from TRACE, SDO, IRIS and ALMA observations
The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter
Detection of spicules termed Rapid Blue-shifted Excursions as seen in the chromosphere via Hα and the transition region via Si iv 1394 Ň line emission
Grid-based imaging in X-rays and gamma-rays with high spatial resolution
It Takes a Village (Invited memoir)
Maximal growth rate of the ascending phase of a sunspot cycle for predicting its amplitude
Starspots Modelling and Flare Analysis on Selected MV Stars
Doubling of minute-long Quasi-Periodic Pulsations from super-flares on a low mass star
Geometric Assumptions in Hydrodynamic Modeling of Coronal and Flaring Loops
Sun-as-a-star Analysis of Hα Spectra of a Solar Flare Observed by SMART/SDDI: Time Evolution of Red Asymmetry and Line Broadening
Searching for quasi-periodic oscillations in astrophysical transients using Gaussian processes
Analysis of the Evolution of a Multi-Ribbon Flare and Failed Filament Eruption

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey

© 2000-2020 Solar Physics Group - Montana State University