Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two Additions to the New Class of Low Accretion-Rate Magnetic Binaries   Two new magnetic white dwarf accretion binaries with extremely low
mass-transfer rates have been discovered in the course of the Sloan Digital Sky
Survey. Measured magnetic fields are 42 MG and 57 MG, and one system orbits
with a period of just 82 min. The new systems therefore significantly expand
the range in properties exhibited by the small class. The measured accretion
rates are very low, 0.6-5x10^{-13} Msun/yr, and multiple visits spanning more
than a year confirm that this is not a short-lived characteristic. It is
becoming increasingly clear that the low-mdot magnetic white dwarf binaries
accrete by nearly complete magnetic capture of the stellar wind from the
secondary star rather than by Roche lobe overflow. The accretion rates
therefore provide some of the first realistic estimates of the total wind loss
rates from M dwarfs. Although one or more of the eight systems known to date
may be interrupted or possibly even extinct Polars, several lines of evidence
suggest that most are pre-Polars whose evolution has not yet brought the
secondaries into contact with their Roche surfaces. Considering the
difficulties of identifying binaries over a wide range in field strength and
accretion rate, it is quite possible that the space density of wind-accreting
magnetic binaries exceeds that of the classical X-ray emitting, Roche-lobe
overflow Polars.

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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
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The categories of this paper are: cond-mat