Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three years in the coronal life of AB Dor. I. Plasma emission measure
  distributions and abundances at different activity levels   The young active star AB Dor (K1 IV-V) has been observed 16 times in the last
three years with the XMM-Newton and Chandra observatories, totalling 650 ks of
high-resolution X-ray spectra. The XMM/RGS observations with the highest and
lowest average emission levels have been selected to study the coronal
properties of AB Dor in two different activity levels. We compare the results
based on the XMM data with those obtained from a higher resolution Chandra/HETG
spectrum, using the same line-based analysis technique. We have reconstructed
the plasma Emission Measure Distribution vs. temperature (EMD) in the range log
T(K) ~ 6.1-7.6, and we have determined the coronal abundances of AB Dor,
obtaining consistent results between the two instruments.The overall shape of
the EMD is also consistent with the one previously inferred from EUVE data. The
EMD shows a steep increase up to the peak at log T (K) ~ 6.9 and a substantial
amount of plasma in the range log T (K) ~ 6.9-7.3. The coronal abundances show
a clear trend of increasing depletion with respect to solar photospheric
values, for elements with increasing First Ionization Potential (FIP), down to
the Fe value ([Fe/H]=-0.57), followed by a more gradual recovery of the
photospheric values for elements with higher FIP. He-like triplets and Fe XXI
and Fe XXII lines ratios indicate electron densities log ne~10.8 cm^-3 at log
T(K) ~ 6.3 and log ne ~ 12.5 at log T(K) ~ 7, implying plasma pressures steeply
increasing with temperature. These results are interpreted in the framework of
a corona composed of different families of magnetic loop structures, shorter
than the stellar radius and in isobaric conditions, having pressures increasing
with the maximum plasma temperature, and which occupy a small fraction (f ~
10^-4 - 10^-6) of the stellar surface.

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The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph