Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A revised calibration of the Mv-W(OI 7774) relationship using Hipparcos
  data: Its application to Cepheids and evolved stars   A new calibration of the Mv-W(OI 7774) relationship has been calculated using
better estimates of reddenings and distances to a sample of 27 calibrator stars
of A-G spectral types, based on accurate parallaxes and proper motions from the
Hipparcos and Tycho catalogues. The present calibration predicts absolute
magnitude with accuracies of $\pm$ 0.38 mag. for a sample covering a large
range of Mv, from -9.5 to $+0.35$ mag.
  The colour term included in a previous paper has been dropped since its
inclusion was not bringing any significant improvement to the calibration. The
variation of the OI 7774 feature in the classical cepheid SS Sct has been
studied. We calculated a phase-dependent correction to random phase OI feature
strengths in Cepheids, such that it predicts mean absolute magnitudes using the
above calibration. After applying such correction, we could increase the list
of calibrators to 58 by adding Mv and OI triplet strength data for 31 classical
Cepheids.
  The standard error of the calibration using the composite sample was
comparable to that obtained from the primary 27 calibrators, showing that it is
possible to calculate mean Cepheid luminosities from random phase observations
of the OI7774 feature. We use our derived calibrations to estimate Mv for a set
of evolved objects to be able to locate their positions in the H-R diagram.

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The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas