Related papers: Cepheid metallicity and Hubble constant

Gravitational wave coalescence events provide an entirely new way to determine the Hubble constant, with the absolute distance calibration provided by the theory of general relativity. This standard siren method was utilized to measure the…

Since the launch of the Hubble Space Telescope nine years ago, Cepheid distances to 25 galaxies have been determined for the purpose of calibrating secondary distance indicators. A variety of these can now be calibrated, and the…

Progressive increases in the precision of the Hubble-constant measurement via Cepheid-calibrated Type Ia supernovae (SNe Ia) have shown a discrepancy of $\sim 4.4\sigma$ with the current value inferred from Planck satellite measurements of…

The distance of the Virgo cluster is derived in the B band from the 21 cm-line width-absolute magnitude relation. The latter is calibrated using 18 spirals with Cepheid distances mainly from HST. The calibration is applied to a complete…

Any calibration of the present value of the Hubble constant requires recession velocities and distances of galaxies. While the conversion of observed velocities into true recession velocities has only a small effect on the result, the…

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 present a measurement of the Hubble constant $H_0$ from surface brightness fluctuation (SBF) distances for 63 bright, mainly early-type galaxies out to 100 Mpc observed with the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the…

Measurement of the distances to nearby galaxies have improved rapidly in recent decades. The ever-present challenge is to reduce systematic effects, especially as greater distances are probed, and the uncertainties become larger. In this…

We present an analysis of Type Ia Supernovae (SNe~Ia) from both the Carnegie Supernova Project~I (CSP-I) and II (CSP-II), and extend the Hubble diagram from the optical to the near-infrared wavelengths ($uBgVriYJH$). We calculate the Hubble…

While the recent discovery of the Cepheid variables in the Virgo cluster galaxies puts additional support for the Hubble constant $H_0 \sim 80$km/sec/Mpc, a relatively lower value $H_0 \sim 50$km/sec/Mpc is suggested by other distance…

We review the use of Cepheids as distance indicators with particular emphasis on the methods which have been applied to HST observations of Cepheids. The calibration of the period-luminosity relations is examined in detail and we identify…

We derive new effective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-field CCD images. These are used in conjunction with recent literature velocity data to construct the fundamental plane (FP) of the…

The Hubble's constant is usually surmised to be a constant; but the experiments show a large spread and conflicting estimates. According to the plasma-redshift theory, the Hubble's constant varies with the plasma densities along the line of…

We present an overview of and preliminary results from an ongoing comprehensive program that has a goal of determining the Hubble constant to a systematic accuracy of 2%. As part of this program, we are currently obtaining 3.6 micron data…

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 have observed the dwarf galaxy IC 1613, at multiple epochs in the mid--infrared using Spitzer and contemporaneously in the near--infrared using the new FourStar near-IR camera on Magellan. We have constructed Cepheid period--luminosity…

We report observations of 240 Cepheid variables obtained with the Near Infrared Camera (NICMOS) through the F160W filter on the Hubble Space Telescope (HST). The Cepheids are distributed across six recent hosts of Type Ia supernovae (SNe…

Evidence is presented which supports findings that the classical Cepheid VIc period-Wesenheit function is relatively insensitive to metallicity. The viability of a recently advocated strong metallicity dependence was evaluated by applying…

Cepheid-based distances to seven Type Ia supernovae (SNe)-host galaxies have been derived using the standard HST Key Project on the Extragalactic Distance Scale pipeline. For the first time, this allows for a transparent comparison of data…

We report observations of two nearby Type Ia supernovae (SNe Ia) for which observations of Cepheid variables in the host galaxies have been obtained with the Hubble Space Telescope: SN 1994ae in NGC 3370 and SN 1998aq in NGC 3982. For NCG…