Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Cepheid Period-Luminosity relation and the maser distance to NGC
  4258   In a recent paper describing HST observations of Cepheids in the spiral
galaxy NGC 4258, Newman et al. (2001) report that the revised calibrations and
methods for the Key Project on the Extragalactic Distance Scale yield that the
true distance modulus of this galaxy is 29.40+-0.09 mag, corresponding to a
metric distance of 7.6+-0.3 Mpc. This Cepheid distance, which holds for 18.50
mag as the true distance modulus of the LMC, is not significantly larger than
7.2+-0.5 Mpc, the value determined by Herrnstein et al. (1999) from purely
geometric considerations on the orbital motions of water maser sources.
However, if the metallicity difference D[O/H]~0.35 between NGC 4258 and LMC is
taken into account, then the Key Project methods lead to a
metallicity-corrected value of 29.47+-0.09 mag, with 18.50 mag for the LMC,
namely to a Cepheid distance of 7.8+-0.3 Mpc, which is 1.2 sigma from the maser
determination. In this paper we show that the metallicity correction on Cepheid
distance determinations, as suggested by pulsation models, might provide the
natural way of reaching a close agreement between Cepheid and maser distance to
NGC 4258 for a wide variety of LMC distance determinations.

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The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th