Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two New Tests of the Metallicity Sensitivity of the Cepheid
  Period-Luminosity Relation (The Leavitt Law)   We undertake a new test of the metallicity sensitivity of the Leavitt Law for
Classical Cepheids. We derive an empirical calibration of the apparent
luminosities of Cepheids as measured from the optical through the mid-infrared
(0.45-8.0um) as a function of spectroscopic [Fe/H] abundances of individual
Cepheids in the Large Magellanic Cloud from Romaniello et al. (2008). The
cumulative trend over the entire wavelength range shows a nearly monotonic
behavior. The sense of the trend is consistent with differential
line-blanketing in the optical, leading to stars of high metallicity being
fainter in the optical. This is followed by a reversal in the trend at longer
wavelengths, with the cross-over occurring near the K band at about 2.2um,
consistent with a subsequent redistribution of energy resulting in a mild
brightening of Cepheids (with increased metallicity) at mid-infrared
wavelengths. This conclusion agrees with that of Romaniello et al. based on a
differential comparison of the mean V- and K-band Leavitt Laws for the Galaxy,
SMC and LMC, but is opposite in sign to most other empirical tests of the
sensitivity of Cepheid distances to mean [O/H] HII region abundances. We also
search for a correlation of Cepheid host-galaxy metallicity with deviations of
the galaxy's Cepheid distance from that predicted from a pure Hubble flow.
Based on Cepheid distances to 26 nearby galaxies in the local flow, only a very
weak signal is detected giving Dmu_o = -0.17 (+/- 0.31) ([O/H] - 8.80) - 0.21
(+/-0.10). This is in agreement with previous determinations, but statistically
inconclusive.

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The categories of this paper are: ao-sci
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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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: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
2
The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn