Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Studies of multiple stellar systems - III. Modulation of orbital
  elements in the triple-lined system HD 109648   The triple-lined spectroscopic triple system HD 109648 has one of the
shortest periods known for the outer orbit in a late-type triple, 120.5 days,
and the ratio between the periods of the outer and inner orbits is small, 22:1.
With such extreme values, this system should show orbital element variations
over a timescale of about a decade. We have monitored the radial velocities of
HD 109648 with the CfA Digital Speedometers for eight years, and have found
evidence for modulation of some orbital elements. While we see no definite
evidence for modulation of the inner binary eccentricity, we clearly observe
variations in the inner and outer longitudes of periastron, as well as in the
radial velocity amplitudes of the three components. The observational results,
combined with numerical simulations, allow us to put constraints on the
orientation of the orbits.

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The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
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The categories of this paper are: econ
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: acc-phys