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 A
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 A is photopumped by
He-like Na X at 11.003 A, which predicts significant intensity
enhancement in the Ne IX 82.76 A 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.
Original language | English |
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Pages (from-to) | 3782-3786 |
Number of pages | 5 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 474 |
Issue number | 3 |
Early online date | 23 Nov 2017 |
DOIs | |
Publication status | Published - 01 Mar 2018 |
Bibliographical note
IN PRESSKeywords
- Astrophysics - Solar and Stellar Astrophysics