Related papers: Galactic and Extragalactic Distance Scales: The Va…

This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the…

A linearity test shows H_0 to decrease by 7% out to 18000 km/s. The value at 10000 km/s is a good approximation to the mean value of Ho over very large scales. The construction of the extragalactic distance scale is discussed. Field…

We report the first results of a long term program aiming to provide accurate independent estimates of the Hubble constant (H0) using the L-sigma distance estimator for Giant extragalactic HII regions (GEHR) and HII galaxies. We have used…

The present status of the distance scale to Galactic globular clusters is reviewed. Six distance determination techniques which are deemed to be most reliable are discussed in depth. These different techniques are used to calibrate the…

Cepheids are the pillar of the extragalactic distance scale, but their reach in distance is not sufficient to calibrate H_0. Yet HST has provided Cepheid distances to eight galaxies which have produced SNe Ia. The latter are used as nearly…

For 100 years since galaxies were found to be flying apart from each other, astronomers have been trying to determine how fast. The expansion, characterized by the Hubble constant, H0, is confused locally by peculiar velocities caused by…

We undertook a long term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder -- M31 and M33 -- using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to…

Current state of the variable stars studies, including halo and globular-cluster variables is briefly discussed, as well as the halo kinematics and modern problems of the Universal distance scale. I propose new approach to the projection…

This is the third in a series of papers studying the variable stars in old globular clusters in the Large Magellanic Cloud. The primary goal of this series is to look at how the characteristics and behavior of RR Lyrae stars in…

The correlation between the luminosities and rotation velocities of galaxies can be used to estimate distances to late-type galaxies. It is an appropriate moment to re-evaluate this method given the great deal of new information available.…

We report the discovery of additional 22 RV Tau stars located in the OGLE-II and OGLE-III fields toward the Galactic bulge, increasing to 357 objects the OGLE-III catalog of type II Cepheids in the Galactic center. Four of the newly…

Using the Hubble Space Telescope (HST) 37 long-period Cepheid variables have been discovered in the Fornax Cluster spiral galaxy NGC 1365. The resulting V and I period-luminosity relations yield a true distance modulus of 31.35 +/- 0.07…

I summarize recent work comparing relative distances measured to individual galaxies with independent methods. The comparisons include: ground-based surface brightness fluctuation (SBF) and fundamental plane distances to 170 galaxies,…

Cepheids and RR Lyrae stars are important pulsating variable stars in distance scale work because they serve as standard candles. Cepheids follow well-defined period-luminosity (PL) relations defined for bands extending from optical to…

Distances measured using Cepheid variable stars have been essential for establishing the cosmological distance scale and the value of the Hubble constant. These stars have remained the primary extragalactic distance indicator since 1929…

We report on the discovery of Cepheids in the Virgo spiral galaxy NGC 4535, based on observations made with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope. NGC 4535 is one of 18 galaxies observed as a part of The…

This work is part of an effort to detect secular variable objects in large scale surveys by analysing their path in color-magnitude diagrams. To this aim, we first present the variability morphologies in the V/V-I diagram of several types…

Six of the principal galaxy distance indicators are discussed: Cepheid variables, the Tully-Fisher relation, the Dn-sigma relation, Surface Brightness Fluctuations, Brightest Cluster Galaxies, and Type Ia Supernovae. The role they play in…

We present new absolute trigonometric parallaxes and proper motions for seven Pop II variable stars: five RR Lyr variables; RZ Cep, XZ Cyg, SU Dra, RR Lyr, UV Oct; and two type 2 Cepheids; VY Pyx and {\kappa} Pav. We obtained these results…

Classical Cepheid and RR Lyrae variables are fundamental tracers of cosmic distances and stellar evolution and pulsation. Light curve analysis and pulsation properties of these radially pulsating stars provide stringent tests for…