Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Evidence of Coexisting EIT Wave and Coronal Moreton Wave from
  SDO/AIA Observations   "EIT waves" are a globally propagating wavelike phenomenon. They were often
interpreted as a fast-mode magnetoacoustic wave in the corona, despite various
discrepancies between the fast-mode wave model and observations. To reconcile
these discrepancies, we once proposed that "EIT waves" are apparent propagation
of the plasma compression due to successive stretching of the magnetic field
lines pushed by the erupting flux rope. According to this model, an "EIT wave"
should be preceded by a fast-mode wave, which however was rarely observed. With
the unprecedented high cadence and sensitivity of the {\em Solar Dynamics
Observatory} ({\em SDO}) observations, we discern a fast-moving wave front with
a speed of 560 km s$^{-1}$, ahead of an "EIT wave", which had a velocity of
$\sim 190$ km s$^{-1}$, in the "EIT wave" event on 2010 July 27. The results,
suggesting that "EIT waves" are not fast-mode waves, confirm the prediction of
our fieldline stretching model for "EIT wave". In particular, it is found that
the coronal Moreton wave was $\sim 3$ times faster than the "EIT wave" as
predicted.

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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: hep-th