X-ray line coincidence photopumping in a solar flare
Abstract
Line coincidence photopumping is a process where the electrons of an atomic or molecular species are radiatively excited through the absorption of line emission from another species at a coincident wavelength. There are many instances of line coincidence photopumping in astrophysical sources at optical and ultraviolet wavelengths, with the most famous example being Bowen fluorescence (pumping of O III 303.80 Å by He II), but none to our knowledge in X-rays. However, here we report on a scheme where a He-like line of Ne IX at 11.000 Å is photopumped by He-like Na X at 11.003 Å, which predicts significant intensity enhancement in the Ne IX 82.76 Å transition under physical conditions found in solar flare plasmas. A comparison of our theoretical models with published X-ray observations of a solar flare obtained during a rocket flight provides evidence for line enhancement, with the measured degree of enhancement being consistent with that expected from theory, a truly surprising result. Observations of this enhancement during flares on stars other than the Sun would provide a powerful new diagnostic tool for determining the sizes of flare loops in these distant, spatially unresolved, astronomical sources.
- Authors:
-
- Queen’s Univ., Belfast (United Kingdom). Astrophysics Research Centre, School of Mathematics and Physics
- Imperial College, London (United Kingdom). Blackett Lab.
- California State Univ. (CalState), Northridge, CA (United States). Dept. of Physics and Astronomy
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Notre Dame, IN (United States). Dept. of Physics
- Publication Date:
- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org.:
- USDOE; European Union (EU)
- OSTI Identifier:
- 1438781
- Report Number(s):
- LLNL-JRNL-739147
Journal ID: ISSN 0035-8711
- Grant/Contract Number:
- AC52-07NA27344; 606862
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Additional Journal Information:
- Journal Volume: 474; Journal Issue: 3; Journal ID: ISSN 0035-8711
- Publisher:
- Royal Astronomical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTRONOMY AND ASTROPHYSICS; line: identification; radiative transfer; Sun: corona; Sun: flares; stars: coronae; stars: flare
Citation Formats
Keenan, F. P., Poppenhaeger, K., Mathioudakis, M., Rose, S. J., Flowerdew, J., Hynes, D., Christian, D. J., Nilsen, J., and Johnson, W. R.. X-ray line coincidence photopumping in a solar flare. United States: N. p., 2017.
Web. doi:10.1093/mnras/stx3035.
Keenan, F. P., Poppenhaeger, K., Mathioudakis, M., Rose, S. J., Flowerdew, J., Hynes, D., Christian, D. J., Nilsen, J., & Johnson, W. R.. X-ray line coincidence photopumping in a solar flare. United States. https://doi.org/10.1093/mnras/stx3035
Keenan, F. P., Poppenhaeger, K., Mathioudakis, M., Rose, S. J., Flowerdew, J., Hynes, D., Christian, D. J., Nilsen, J., and Johnson, W. R.. Thu .
"X-ray line coincidence photopumping in a solar flare". United States. https://doi.org/10.1093/mnras/stx3035. https://www.osti.gov/servlets/purl/1438781.
@article{osti_1438781,
title = {X-ray line coincidence photopumping in a solar flare},
author = {Keenan, F. P. and Poppenhaeger, K. and Mathioudakis, M. and Rose, S. J. and Flowerdew, J. and Hynes, D. and Christian, D. J. and Nilsen, J. and Johnson, W. R.},
abstractNote = {Line coincidence photopumping is a process where the electrons of an atomic or molecular species are radiatively excited through the absorption of line emission from another species at a coincident wavelength. There are many instances of line coincidence photopumping in astrophysical sources at optical and ultraviolet wavelengths, with the most famous example being Bowen fluorescence (pumping of O III 303.80 Å by He II), but none to our knowledge in X-rays. However, here we report on a scheme where a He-like line of Ne IX at 11.000 Å is photopumped by He-like Na X at 11.003 Å, which predicts significant intensity enhancement in the Ne IX 82.76 Å transition under physical conditions found in solar flare plasmas. A comparison of our theoretical models with published X-ray observations of a solar flare obtained during a rocket flight provides evidence for line enhancement, with the measured degree of enhancement being consistent with that expected from theory, a truly surprising result. Observations of this enhancement during flares on stars other than the Sun would provide a powerful new diagnostic tool for determining the sizes of flare loops in these distant, spatially unresolved, astronomical sources.},
doi = {10.1093/mnras/stx3035},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 3,
volume = 474,
place = {United States},
year = {2017},
month = {11}
}
Web of Science
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