Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Periodicities in the K2 lightcurve of HP Librae   We analyse Kepler/K2 lightcurve data of the AM CVn system HP Librae. We
detect with confidence four photometric periodicities in the system: the
orbital frequency, both positive and negative superhumps, and the positive
apsidal precession frequency of the accretion disc. This is only the second
time that the apsidal precession frequency has ever been directly detected in
the photometry of a helium accreting system, after SDSS J135154.46-064309.0. We
present phase-folded lightcurves and sliding power spectra of each of the four
periodicities. We measure rates of change of the positive superhump period of
$10^{-7}$ days/day. We also redetect a QPO at 300 cyc/day, a feature that has
been stable over decades, and show that it is harmonically related to two other
QPOs, the lowest of which is centered on the superhump/orbital frequency. The
continuum power spectrum is consistent with a single power law with no evidence
of any breaks within our observed frequency range.

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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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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: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat