Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On a new and homogeneous metallicity scale for Galactic classical
  Cepheids - I. Physical parameters   We gathered more than 1130 high-resolution optical spectra for more than 250
Galactic classical Cepheids. The spectra were collected with different optical
spectrographs: UVES at VLT, HARPS at 3.6m, FEROS at 2.2m MPG/ESO, and STELLA.
To improve the effective temperature estimates, we present more than 150 new
line depth ratio (LDR) calibrations that together with similar calibrations
already available in the literature allowed us to cover a broad range in
wavelength (between 5348 and 8427 angstrom) and in effective temperatures
(between 3500 and 7700 K). This means the unique opportunity to cover both the
hottest and coolest phases along the Cepheid pulsation cycle and to limit the
intrinsic error on individual measurements at the level of ~100 K. Thanks to
the high signal-to-noise ratio of individual spectra we identified and measured
hundreds of neutral and ionized lines of heavy elements, and in turn, have the
opportunity to trace the variation of both surface gravity and microturbulent
velocity along the pulsation cycle. The accuracy of the physical parameters and
the number of Fe I (more than one hundred) and Fe II (more than ten) lines
measured allowed us to estimate mean iron abundances with a precision better
than 0.1 dex. Here we focus on 14 calibrating Cepheids for which the current
spectra cover either the entire or a significant portion of the pulsation
cycle. The current estimates of the variation of the physical parameters along
the pulsation cycle and of the iron abundances agree quite well with similar
estimates available in the literature. Independent homogeneous estimates of
both physical parameters and metal abundances based on different approaches
that can constrain possible systematics are highly encouraged.

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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
9
The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: math