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Neutral Hydrogen and its Emission Lines in the Solar Corona View all abstracts by submitter

Jean-Claude Vial   Submitted: 2016-09-16 08:16

Since the Lα rocket observations of (Gabriel, Solar Phys. 21, 392,1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisionnal and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five radii. We compare our results with previous computations and observations (e.g. Lα from UVCS) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 A wide) bandpass filter.

Authors: Jean-Claude Vial, Martine Chane-Yook
Projects: None

Publication Status: Solar Physics (accepted)
Last Modified: 2016-09-17 07:04
Go to main E-Print page  Comparison of 30 THz impulsive burst time development to microwaves, Hα, EUV, and GOES soft X-rays  Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

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