Bibcode
Coppola, G.; Stetson, P. B.; Marconi, M.; Bono, G.; Ripepi, V.; Fabrizio, M.; Dall'Ora, M.; Musella, I.; Buonanno, R.; Ferraro, I.; Fiorentino, G.; Iannicola, G.; Monelli, M.; Nonino, M.; Pulone, L.; Thévenin, F.; Walker, A. R.
Bibliographical reference
The Astrophysical Journal, Volume 775, Issue 1, article id. 6, 12 pp. (2013).
Advertised on:
9
2013
Journal
Citations
24
Refereed citations
22
Description
We present new optical (BVI) time-series data for the evolved variable
stars in the Carina dwarf spheroidal galaxy. The quality of the data and
the observing strategy allowed us to identify 14 new variable stars.
Eight out of the 14 are RR Lyrae (RRL) stars, 4 are Anomalous Cepheids
(ACs), and 2 are geometrical variables. Comparison of the period
distribution for the entire sample of RRLs with similar distributions in
nearby dwarf spheroidal galaxies and in the Large Magellanic Cloud
indicates that the old stellar populations in these systems share
similar properties. This finding is also supported by the RRL
distribution in the Bailey diagram. On the other hand, the period
distribution and the Bailey diagram of ACs display significant
differences among the above stellar systems. This evidence suggests that
the properties of intermediate-age stellar populations might be affected
both by environmental effects and structural parameters. We use the BV
Period-Wesenheit (PW) relation of RRLs together with evolutionary
prescriptions and find a true distance modulus of 20.09 ± 0.07
(intrinsic) ± 0.1 (statistical) mag that agrees quite well with
similar estimates available in the literature. We identified four
peculiar variables. Taking into account their position in the Bailey
diagram and in the BV PW relation, two of them (V14 and V149) appear to
be candidate ACs, while two (V158 and V182) might be peculiar RRLs. In
particular, the variable V158 has a period and a V-band amplitude very
similar to the low-mass RRL—RRLR-02792—recently identified
by Pietrzyński et al. in the Galactic bulge.
Based on images collected with the MOSAICII camera available at the CTIO
4 m Blanco telescope, La Serena (2003B-0051, 2004B-0227, and
2005B-0092; PI: A. R. Walker) and in part with the WFI available at the
2.2 m MPG/ESO telescope (A064.L-0327) and with images obtained from
the ESO/ST-ECF Science Archive Facility.
Related projects
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli