Observations and Modelling of Helium Lines in Solar Flares

Simoes, P. , Fletcher, L. , Labrosse, N. and Kerr, G. (2016) Observations and Modelling of Helium Lines in Solar Flares. In: Coimbra Solar Physics Meeting 2015: Ground-based Solar Observations in the Space Instrumentation Era, Coimbra, Portugal, 5-9 Oct 2015, p. 197. ISBN 9781583818923



Publisher's URL: http://www.aspbooks.org/a/volumes/article_details?paper_id=37735


We explore the response of the He II 304 Å and He I 584 Å line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the intensities of both He lines are very sensitive to the energy flux deposited in the chromosphere, or more specifically to the heating rate, with He II 304 {\AA} being more sensitive to the heating than He I 584 {\AA}. Therefore, the He line ratio increases for larger heating rates in the chromosphere. A similar trend is found in observations, using SDO/EVE He irradiance ratios and estimates of the electron beam energy rate obtained from hard X-ray data. From the simulations, we also found that spectral index of the electrons can affect the He ratio but a similar effect was not found in the observations.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Kerr, Graham and Simoes, Dr Paulo and Fletcher, Professor Lyndsay and Labrosse, Dr Nicolas
Authors: Simoes, P., Fletcher, L., Labrosse, N., and Kerr, G.
Subjects:Q Science > QB Astronomy
College/School:College of Science and Engineering > School of Physics and Astronomy
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
595181Chromospheric Flares: Observations, Models and Archives (CHROMA)Lyndsay FletcherEuropean Commission (EC)606862P&A - PHYSICS & ASTRONOMY