Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The MACHO Project LMC Variable Star Inventory: The Discovery of RV Tauri
  stars and New Type II Cepheids in the LMC   We report the discovery of RV Tauri stars in the Large Magellanic Cloud. In
light and colour curve behaviour, the RV Tauri stars appear to be a direct
extension of the type II Cepheids to longer periods. A single period-
luminosity-colour relationship is seen to describe both the type II Cepheids
and the RV Tauri stars in the LMC. We derive the relation: $V_{\circ} = 17.89
(\pm 0.20) - 2.95 (\pm 0.12) \log_{10}P + 5.49 (\pm 0.35) \bar{(V-R)_{\circ}}$,
valid for type II Cepheids and RV Tauri stars in the period range $0.9 <
\log_{10}P < 1.75$. Assuming a distance modulus to the Large Magellanic Cloud
of 18.5, the relation in terms of the absolute luminosities becomes: $M_{V} =
-0.61 (\pm 0.20) - 2.95 (\pm 0.12) \log_{10}P + 5.49 (\pm 0.35)
\bar{(V-R)_{\circ}}$.

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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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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: funct-an
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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: math
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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org