Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Solar Flare Calcium Abundances with no Surprises: Results from the
  SMM Bent Crystal Spectrometer   The calcium abundance in flare plasmas is estimated using X-ray spectra from
the Solar Maximum Mission Bent Crystal Spectrometer (BCS) during the decays of
194 flares (GOES classifications from B6.4 to X13) occurring between 1980 and
1989. Previous work by Sylwester et al. found that the abundance varied from
flare to flare. That analysis is improved on here using updated instrument
parameters and by including all calcium lines viewed by the BCS instead of only
the resonance line, so greatly enhancing the photon count statistics. The
abundance variations are confirmed with the average abundance, $A({\rm Ca})$
(expressed logarithmically with $A({\rm H}) = 12$), equal to $6.77 \pm 0.20$
for 194 flares (141 of which are new in this study). This range corresponds to
factors of between 1.7 and 7.2 larger than the photospheric abundance and so
our results are in line with a ``FIP" (first ionization potential) effect
whereby low-FIP elements like Ca (FIP = 6.11~eV) have enhanced coronal
abundances. The Ca flare abundance is uncorrelated with solar activity indices,
but weak correlations are suggested with GOES flare class and duration (larger
$A({\rm Ca})$ for smaller and shorter flares). The ponderomotive force theory
of Laming explaining the FIP effect gives a range of parameters within which
our estimates of $A({\rm Ca})$ agree with the theory. However, this then gives
rise to disagreements with previous estimates of the flare silicon and sulfur
abundances, although those of argon and iron are in good agreement. Small
adjustments of the theory may thus be necessary.

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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex