The OGLE-III Catalog of Variable Stars

VIII. Type II Cepheids in the Small Magellanic Cloud

The eighth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains type II Cepheids in the Small Magellanic Cloud (SMC). The sample consists of 43 objects, including 17 BL Her, 17 W Vir and 9 RV Tau stars (first examples ever found in the SMC). Seven stars have been classified as peculiar W Vir stars - a recently identified subclass of type II Cepheids. These stars have distinctive light curves, are brighter and bluer than the ordinary W Vir variables. We confirm that a large fraction of the peculiar W Vir stars are members of binary systems.

RV Tauri stars in the SMC

Three type II Cepheids exhibit eclipsing variations superimposed on the pulsation light curves, and three other objects show long-period ellipsoidal variability. All stars with the indication of binarity display secondary periods which may be interpreted as amplitude and/or phase modulations of the pulsation light curves with periods equal to the orbital periods or half the orbital periods. We do not have any model for these modulations, however this phenomenon rules out a possibility of the optical blends of a pulsating star and a binary system.

Type II Cepheids in eclipsng binary systems

For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.

Period-luminosity relation for Cepheids in the SMC

PLEASE cite the following paper when using the data or referring to these OGLE results:
Soszyński et al., 2010, Acta Astron., 60, 91 (arXiv:1005.3544)

Any comments about the data and the form of their presentation are welcome as they can improve the future releases of catalogs of variable stars detected by the OGLE collaboration. Send your messages to this address.