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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 225806.0, MPI für Astronomie / Publikationen_mpia
The variable-star population in Phoenix:
Coexistence of anomalous and short-period
classical Cepheids and detection of RR Lyrae
Authors:Gallart, C.; Aparicio, A.; Freedman, W. L.; Madore, B. F.; Martínez-Delgado, D.; Stetson, P. B.
Date of Publication (YYYY-MM-DD):2004
Title of Journal:The Astronomical Journal
Start Page:1486
End Page:1501
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present the results of a search for
variable stars in the Local Group dwarf galaxy
Phoenix. Nineteen Cepheids, six candidate
long-period variables, one candidate eclipsing
binary, and a large number of candidate RR Lyrae
stars have been identified. Periods and light
curves have been obtained for all the Cepheid
variables. Their distribution in the
period-luminosity diagram reveals that both
anomalous Cepheids (ACs) and short-period
classical Cepheids (s-pCC's) are found in our
sample. This is the first time that both types
of variable stars are identified in the same
system even though they likely coexist, but have
gone unnoticed so far, in other low-metallicity
galaxies such as Leo A and Sextans A. We argue
that the conditions for the existence of both
types of variable stars in the same galaxy are a
low metallicity at all ages and the presence of
both young and intermediate-age (or old,
depending on the nature of AC) stars. The RR
Lyrae candidates trace, together with the
well-developed horizontal branch, the existence
of an important old population in Phoenix. The
different spatial distributions of s-pCC's, ACs,
and RR Lyrae variables in the Phoenix field are
consistent with the stellar population gradients
found in Phoenix, in the sense that the younger
population is concentrated in the central part of
the galaxy. The gradients in the distribution of
the young population within the central part of
Phoenix, which seem to indicate a propagation of
the recent star formation, are also reflected in
the spatial distribution of the s-pCC's.
Free Keywords:Stars: Variables: Cepheids; galaxies:
; individual (Phoenix dwarf); Galaxies: Local
; Group; Stars: Variables: RR Lyrae Variable
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:Canarias, E-38200 La Laguna, Tenerife, Spain;
<EMAIL>aaj@iac.es</EMAIL>; Ramon y Cajal Fellow,
Instituto de Astrof‚‚iacute;sica de Canarias.),
AB(Instituto de Astrof‚‚iacute;sica de Canarias,
E-38200 La Laguna, Tenerife, Spain;
<EMAIL>aaj@iac.es</EMAIL>), AC(Observatories of
the Carnegie Institution of Washington, 813 Santa
Barbara Street, Pasadena, CA 91101;
<EMAIL>wendy@ociw.edu</EMAIL>), AD(Infrared
Processing and Analysis Center, Mail Stop 100-22,
California Institute of Technology, Pasadena, CA
91125; <EMAIL>barry@ipac.caltech.edu</EMAIL>),
AE(Max-Planck-Institut f‚‚uuml;r Astronomie,
K‚‚ouml;nigstuhl 17, D-69117 Heidelberg, Germany;
AF(Herzberg Institute of Astrophysics, National
Research Council, Victoria, BC V9E 2E7, Canada;
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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