Related papers: A Cepheid distance to NGC 4258
We present the results of near-infrared observations of extragalactic Cepheids made with the Near Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope. The variables are located in the galaxies IC 1613, IC 4182,…
Using high-quality observed period-luminosity relations in both Magellanic Clouds in VIJHKs bands and optical and near-infrared Wesenheit indices we determine the effect of metallicity on Cepheid P-L relations by comparing the relative…
Context: The bright southern Cepheid RS Pup is surrounded by a circumstellar nebula reflecting the light from the central star. The propagation of the light variations from the Cepheid inside the dusty nebula creates spectacular light…
The ACS Nearby Galaxy Survey Treasury (ANGST) has acquired deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. These data were obtained over a total of 20 HST orbits, providing a baseline long enough to reliably…
Recent estimates of the Cepheid distance modulus of NGC 6822 differ by 0.18 mag. To investigate this we present new multi-epoch JHKs photometry of classical Cepheids in the central region of NGC 6822 and show that there is a zero-point…
We recently showed that rotation significantly affects most observable Cepheid quantities, and that rotation, in combination with the evolutionary status of the star, can resolve the long-standing Cepheid mass discrepancy problem. We…
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…
I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first…
An analysis of the Ultra Long Period Cepheids (ULPs) properties could significantly contribute to understanding the Hubble constant tension, e.g. the current discrepancy between determinations based on local distance indicators and those…
We obtain a robust, non-parametric, estimate of the Hubble constant from galaxy linear diameters calibrated using HST Cepheid distances. Our method is independent of the parametric form of the diameter function and the spatial distribution…
We have used the infrared surface brightness technique to obtain a new absolute calibration of the Cepheid PL relation in optical and near-infrared bands from improved data on Galactic stars. The infrared surface brightness distances to the…
Attempts to measure extragalactic distances over the last 90 years are briefly described. It follows a short history of the discovery of the expansion of space. Reasons are discussed for the decrease of the Hubble constant from Ho~500…
Cepheid masses continue to be important tests of evolutionary tracks for intermediate mass stars as well as important predictors of their future fate. For systems where the secondary is a B star, {\it Hubble Space Telescope} ultraviolet…
The photometric data for 460 classical, fundamental-mode Cepheids in the SMC with log P > 0.4 measured by Udalski et al. have been analyzed for their P-C and P-L relations, and for the variation of amplitude across the instability strip in…
We present Period-Luminosity-Color and Period-Luminosity relations of classical Cepheids constructed for about 1280 Cepheids from the LMC and 2140 from the SMC. High quality BVI observations (120-360 epochs in the I-band and 15-40 in the…
In this work, we updated the catalog of Galactic Cepheids with $24\mu\mathrm{m}$ photometry by cross-matching the positions of known Galactic Cepheids to the recently released MIPSGAL point source catalog. We have added 36 new sources…
HST has so far provided Cepheid distances to nine galaxies. Although not sufficient yet to determine the distance of the extended Virgo cluster, they are decisive for the distance scale in two ways. (1) Seven of the galaxies contribute to a…
The distance modulus of a galaxy determined from Cepheids differs from its distance modulus determined from Tully-Fisher by an amount that is proportional to the galaxy's line width, W: Delta mu ~ (-1.73\pm 0.46)log(W). While a…
Hipparcos parallaxes have recently become available for a sample of Galactic Cepheids, and we have used these new distances to calibrate the Cepheid period-luminosity (PL) relation at six wavelengths (BVIJHK). Comparing these calibrations…
The universality of the Cepheid Period-Luminosity relations has been under discussion since metallicity effects have been assumed to play a role in the value of the intercept and, more recently, of the slope of these relations. The goal of…