Related papers: Temperature Differences in the Cepheid Instability…
In this paper, we derive a physical argument for the existence of Period-luminosity and period-luminosity-colour relations at maximum light. We examine in detail a sample of Cepheids in the Large Magellanic Cloud, and compare the variance…
In this paper, we construct full amplitude non-linear hydrodynamical models of fundamental mode Galactic Cepheids and analyze the resulting theoretical period-colour and amplitude-colour relations at maximum, mean and minimum light. These…
We first discuss why there remains continuing, strong motivation to investigate Hubble's Constant. Then we review new evidence from an investigation of the Galactic Open Clusters containing Cepheids by Hoyle et al. that the metallicity…
We undertake a new test of the metallicity sensitivity of the Leavitt Law for Classical Cepheids. We derive an empirical calibration of the apparent luminosities of Cepheids as measured from the optical through the mid-infrared (0.45-8.0um)…
We investigate how a different calibration of the Cepheid Period-Luminosity (PL) relation taking into account the metallicity corrections, affects the absolute magnitude calibration of Supernovae (SNe) Ia and, in turn, the determination of…
We have applied the infrared surface brightness (ISB) technique to derive distances to 13 Cepheid variables in the LMC which have periods from 3-42 days. The corresponding absolute magnitudes define PL relations in VIWJK bands which agree…
Recent HST determinations of the expansion's rate of the Universe (the Hubble constant, H_0) assumed that the Cepheid Period-Luminosity relation at V and I are independent of metallicity (Freedman, et al., 1996, Saha et al., 1996, Tanvir et…
The technique of line depth ratios (LDR) is one of the methods to determine the effective temperature of a star. They are crucial in the spectroscopic studies of variable stars like Cepheids since no simultaneous photometry is usually…
We present the first period-luminosity (PL) and period-Wesenheit (PW) relations in the Sloan-Pans-STARRS gP1rP1iP1 bands for classical fundamental mode Cepheids in the Milky Way. We used a relatively modest number of 76 stars for the PL and…
Pulsation period of Cepheids should change as stars evolve through the instability strip. Rates of these changes found by other authors based on the decades-long O-C diagrams show rather good agreement with theoretical predictions. We have…
We revisit the problem of the positive correlation between age and Galactocentric distance seen in Galactic Classical Cepheids, which at first sight may seem counter-intuitive in the context of inside-out galaxy formation. To explain it, we…
The Cepheid Period-Luminosity (PL) relation is the key tool for measuring astronomical distances and for establishing the extragalactic distance scale. In particular, the local value of the Hubble constant ($H_0$) strongly depends on…
We perform a detailed analysis of Cepheids in NGC 4258, Magellanic Clouds and Milky Way in order to verify the reliability of the theoretical scenario based on a large set of nonlinear convective pulsation models. We derive Wesenheit…
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…
We compared period changes derived from O-C diagrams for 63 classical Cepheids from our Galaxy with model calculations. We found that for Cepheids with log P > 1.0 the observed changes are smaller than predicted values, except variable SZ…
It has been claimed that Period-Luminosity relations derived from infrared observations of Large Magellanic Cloud (LMC) Cepheids are less dependent on the metallicity of the Cepheids. In this work, infrared observations of LMC Cepheids from…
Aims. This study aims to determine empirical intrinsic edges of the classical Cepheids instability strip (IS) in the Small Magellanic Cloud (SMC) galaxy, considering various effects that alter its shape, and compare them with theoretical…
We investigate the luminosity-temperature ($L$-$T$) relation of galaxy clusters as a probe for testing modified gravity (MG) theories, focusing on $f(R)$ gravity and symmetron models. Using an improved semi-analytic framework that…
In spite of the relevance of Classical Cepheids as primary distance indicators, a general consensus on the dependence of the Period-Luminosity (PL) relation on the Cepheid chemical composition has not been achieved yet. From the theoretical…
In a recent paper, we investigated possible systematic uncertainties related to the Cepheid color-luminosity calibration method and their influence on the tension between the Hubble constant as inferred from distances to Type Ia supernovae…