Issue |
A&A
Volume 632, December 2019
|
|
---|---|---|
Article Number | A20 | |
Number of page(s) | 11 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361/201834735 | |
Published online | 21 November 2019 |
Measuring relative abundances in the solar corona with optimised linear combinations of spectral lines
Institut d’Astrophysique Spatiale, CNRS/Université Paris-Sud, Université Paris-Saclay, Bâtiment 121, Université Paris-Sud, 91405 Orsay Cedex, France
e-mail: natalia.zambranaprado@ias.u-psud.fr
Received:
28
November
2018
Accepted:
30
September
2019
Context. Elemental abundances in some coronal structures differ significantly from photospheric abundances, with a dependence on the first ionization potential (FIP) of the element. Measuring these FIP-dependent abundance biases is important for coronal and heliospheric physics.
Aims. We aim to build a method for optimal determination of FIP biases in the corona from spectroscopic observations in a way that is in practice independent from differential emission measure (DEM) inversions.
Methods. We optimised linear combinations of spectroscopic lines of low-FIP and high-FIP elements so that the ratio of the corresponding radiances yields the relative FIP bias with good accuracy for any DEM in a small set of typical DEMs.
Results. These optimised linear combinations of lines allow retrieval of a test FIP bias map with good accuracy for all DEMs in the map. The results also compare well with a FIP bias map obtained from observations using a DEM-dependent method.
Conclusions. The method provides a convenient, fast, and accurate way of computing relative FIP bias maps. It can be used to optimise the use of existing observations and the design of new observations and instruments.
Key words: techniques: spectroscopic / Sun: abundances / Sun: corona / Sun: UV radiation
© N. Zambrana Prado and É. Buchlin 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.