Related papers: The period-luminosity relation for type II Cepheid…

Recent work on the luminosities of type II Cepheids (CephIIs) and RR Lyrae variables is reviewed.In the near infrared (JHKs) the CephIIs in globular clusters show a narrow, linear, period-luminosity relation over their whole period range…

JHKs magnitudes corrected to mean intensity are estimated for LMC type II Cepheids in the OGLE-III survey. Period-luminosity (PL) relations are derived in JHKs as well as in a reddening-free VI parameter. Within the uncertainties the BL Her…

We have estimated JHKs magnitudes corrected to mean intensity for LMC type II Cepheids found in the OGLE-III survey. Period-luminosity relations (PLRs) are derived in JHKs as well as in a reddening-free VI parameter. The BL Her stars (P<4d)…

We present time-series observations of Population \rom{2} Cepheids in the Large Magellanic Cloud at near-infrared ($JHK_s$) wavelengths. Our sample consists of 81 variables with accurate periods and optical ($VI$) magnitudes from the OGLE…

We report the discovery of RV Tauri stars in the Large Magellanic Cloud. In light and colour curve behaviour, the RV Tauri stars appear to be a direct extension of the type II Cepheids to longer periods. A single period- luminosity-colour…

Globular clusters are both primary fossils of galactic evolution and formation and are ideal laboratories for constraining the evolution of low-mass and metal-poor stars. RR Lyrae and type II Cepheid variables are low-mass, radially…

Period-luminosity relations (PLRs) of type II Cepheids (T2Cs) in the Small Magellanic Cloud are derived based on OGLE-III, IRSF/SIRIUS and other data, and these are compared with results for the Large Magellanic Cloud and Galactic globular…

In the second part of the OGLE-III Catalog of Variable Stars (OIII-CVS) we present 197 type II Cepheids and 83 anomalous Cepheids in the Large Magellanic Cloud (LMC). The sample of type II Cepheids consists of 64 BL Her stars, 96 W Vir…

We present near infrared velocity curves for 12 long period variables (LPVs) in the globular cluster 47 Tuc (NGC 104). New light curves are also presented for these variables. Results are compared with the period-luminosity sequences…

We identified a sample of 88 bona fide Population II Cepheids (henceforth referred to as Cepheids) and 44 candidates in Galactic globular clusters (GCs). Seventy-eight of the Cepheids in the sample align within $2\,\sigma$ of the…

[Abridged] We present the results of a Hubble Space Telescope snapshot program to survey the inner region of the globular cluster NGC 6441 for its variable stars. A total of 57 variable stars was found including 38 RR Lyrae stars, 6…

Type II Cepheids are pulsating stars that can be used as standard candles for old stellar populations due to their characteristic Period-Luminosity and Period-Luminosity-Colour relations. They are traditionally divided in 3 sub-classes,…

This paper discusses the current uncertainties in luminosity calibration of the RR Lyrae variables. The difference in distance moduli between the SMC and LMC as derived from RR Lyrae stars and classical Cepheids is used to estimate a…

We obtained a series of more than two hundred R-band CCD images for the crowded central (115"x77") region of the metal-poor globular cluster M15 with an angular resolution of 0.5"-0.9" in most images. Optimal image subtraction was used to…

Infrared and optical absolute magnitudes are derived for the type II Cepheids kappa Pav and VY Pyx from revised Hipparcos parallaxes and for kappa Pav, V553 Cen and SW Tau from pulsation parallaxes. Phase-corrected JHK mags are given for…

We present the first gri-band period-luminosity (PL) and period-Wesenheit (PW) relations for 37 Type II Cepheids (hereafter TIIC) located in 18 globular clusters based on photometric data from the Zwicky Transient Facility. We also updated…

We analyze Galactic, Large Magellanic Cloud and Small Magellanic Cloud Cepheids and RR Lyrae variables in terms of period-color (PC) and amplitude-color (AC) diagrams at the phases of maximum and minimum light. We compiled Galactic Cepheids…

NGC 6441 is a bulge globular cluster with an unusual horizontal branch morphology and a rich population of RR Lyrae (RRL) and Type II Cepheid (T2C) variables that is unexpected for its relatively high metallicity. We present near-infrared…

The Galactic center (GC) is the densest region of the Milky Way. Variability surveys towards the GC potentially provide the largest number of variable stars per square degree within the Galaxy. However, high stellar density is also a…

We present B, V and I CCD light curves for 101 variable stars belonging to the globular cluster NGC2419, 60 of which are new discoveries, based on datasets obtained at the TNG, SUBARU and HST telescopes. The sample includes 75 RR Lyrae…