THE CARINA PROJECT. VI. THE HELIUM-BURNING VARIABLE STARS

Journal Article · Fri Sep 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/775/1/6· OSTI ID:22133842

Coppola, G.; Marconi, M.; Ripepi, V.; Dall'Ora, M.; Musella, I. ^[1]; Stetson, P. B. ^[2]; Bono, G.; Buonanno, R. ^[3]; Fabrizio, M. ^[4]; Ferraro, I.; Iannicola, G.; Pulone, L. ^[5]; Fiorentino, G. ^[6]; Monelli, M. ^[7]; Nonino, M. ^[8]; Thevenin, F. ^[9]

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1. INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy)
2. Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
3. Dipartimento di Fisica-Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma (Italy)
4. INAF-Osservatorio Astronomico di Collurania, via M. Maggini, I-64100 Teramo (Italy)
5. INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy)
6. INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
7. Instituto de Astrofisica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain)
8. INAF-Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-40131 Trieste (Italy)
9. Universite de Nice-Sophia Antipolis, Lab. Lagrange, UMR 7293, Observatoire de la Cote dAzur, BP 4229, F-06304 Nice (France)

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 Pietrzynski et al. in the Galactic bulge.

• OSTI ID: 22133842
• Journal Information: Astrophysical Journal, Vol. 775, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMPLITUDES
CEPHEIDS
DISTANCE
ENVIRONMENTAL EFFECTS
HELIUM BURNING
MAGELLANIC CLOUDS
MASS