Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tidally excited oscillations in MACHO 80.7443.1718: Changing amplitudes
  and frequencies, high-frequency tidally excited mode, and a decrease in the
  orbital period   Eccentric ellipsoidal variables (aka heartbeat stars) is a class of eccentric
binaries in which proximity effects, tidal distortion due to time-dependent
tidal potential in particular, lead to measurable photometric variability close
to the periastron passage. The varying tidal potential may also give rise to
tidally-excited oscillations (TEOs). TEOs may play an important role in the
dynamical evolution of massive eccentric systems. Our study is aimed at the
detection of TEOs and characterisation of the long-term behaviour of their
amplitudes and frequencies in the extreme-amplitude heartbeat star MACHO
80.7443.1718, consisting of a blue supergiant and a late O-type massive dwarf.
We use two seasons of Transiting Exoplanet Survey Satellite (TESS) observations
of the target to obtain new 30-min cadence photometry by means of the
difference image analysis of TESS full-frame images. In order to extend the
analysis to longer time scales, we supplement the TESS data with 30-years long
ground-based photometry of the target. We confirm the detection of the known
$n=23$, 25, and 41 TEOs and announce the detection of two new TEOs, with $n=24$
and 230, in the photometry of MACHO 80.7443.1718. Amplitudes of all TEOs were
found to vary on a time scale of years or months. For $n=25$ TEO amplitude and
frequency changes are related, which may indicate that the main cause of the
amplitude drop of this TEO in TESS observations is the change of its frequency
and increase of detuning parameter. The light curve of the $n=230$ TEO is
strongly non-sinusoidal. Its high frequency may indicate that the oscillation
is a strange mode. We also find that the orbital period of the system decreases
at the rate of about 11 s(yr)$^{-1}$, which can be explained by a significant
mass loss or mass transfer in the system with a possible contribution from
tidal dissipation.

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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg