Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Enigma of the Open Cluster M29 (NGC 6913) Solved   Determining the distance to the open cluster M29 (NGC 6913) has proven
difficult, with distances determined by various authors differing by a factor
of two or more. To solve this problem, we have initiated a new photometric
investigation of the cluster in the Vilnius seven-color photometric system
supplementing it with available data in the BV and JHK_s photometric systems,
and spectra of the nine brightest stars of spectral classes O and B.
Photometric spectral classes and luminosities of 260 stars in a 15 arcmin x 15
arcmin area down to V = 19 mag are used to investigate the interstellar
extinction run with distance and to estimate the distance of the Great Cygnus
Rift, 800 pc. The interstellar reddening law in the optical and near-infrared
regions is found to be close to normal, with the ratio of extinction to color
excess R(BV) = 2.87. The extinction A(V) of cluster members is between 2.5 to
3.8 mag, with a mean value of 2.97 mag or E(B-V) = 1.03. The average distance
of eight stars of spectral types O9-B2 is 1.54 +- 0.15 kpc. Two stars from the
seven brightest ones are field stars: HDE 229238 is a background B0.5
supergiant and HD 194378 is a foreground F star. In the intrinsic
color-magnitude diagram, seven fainter stars of spectral classes B3-B8 are
identified as possible members of the cluster. The 15 selected members of the
cluster of spectral classes O9--B8 plotted on the log L/L(sun) vs. log T(eff)
diagram, together with the isochrones from the Padova database, give the age of
the cluster as 5 +- 1 Myr.

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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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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: q-alg
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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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: hep-lat