Related papers: Blending of Cepheids in M33

Revised Hipparcos parallaxes for classical Cepheids are analysed together with 10 HST-based parallaxes (Benedict et al.). In a reddening-free V,I relation we find that the coefficient of logP is the same within the uncertainties in our…

Cepheids are key distance indicators and benchmarks for stellar evolution, yet most of them are members of binary or multiple systems. While spectroscopic surveys and Gaia proper-motion anomalies reveal a high binary fraction, the…

Using the M31 PAndromeda Cepheid sample and the HST PHAT data we obtain the largest Cepheid sample in M31 with HST data in four bands. For our analysis we consider three samples: A very homogeneous sample of Cepheids based on the PAndromeda…

We apply the image subtraction method to re-analyze the ESO Very Large Telescope data on M83 (NGC 5236), obtained and analyzed by Thim et al. Whereas Thim et al. found 12 Cepheids with periods between 12-55 days, we find 112 Cepheids with…

With this paper we continue the preparation for a forthcoming summary report of our experiment with the Hubble Space Telescope (HST) to determine the Hubble constant using type Ia supernovae as standard candles. Two problems are addressed.…

The three rung distance ladder, which calibrates Type Ia supernovae through stellar distances linked to geometric measurements, provides the highest precision direct measurement of the Hubble constant. In light of the Hubble tension, it is…

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 present the result of BVI photometry, obtained by using FORS@VLT, of the Cepheids present in the field of the Large Magellanic Cloud cluster NGC 1866. We found the 22 known variables plus an additional new Cepheid located about 10' from…

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…

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…

We present HST photometry of a selected sample of 50 long-period, low-extinction Milky Way Cepheids measured on the same WFC3 F555W, F814W, and F160W-band photometric system as extragalactic Cepheids in SN Ia hosts. These bright Cepheids…

We derive the basic properties of seven Galactic open clusters containing Cepheids and construct their period-luminosity (P-L) relations. For our cluster main-sequence fitting we extend previous Hyades-based empirical color-temperature…

We present new parallax measurements of 7 long-period (> 10 days) Milky Way Cepheids (SS CMa, XY Car, VY Car, VX Per, WZ Sgr, X Pup and S Vul) using astrometry from spatial scanning of WFC3 on HST. Observations were obtained at 6 month…

The discovery of large number of Cepheid variables in far-off galaxies offers a unique opportunity to determine the accurate distance of the host galaxy through their period-luminosity relation. The main aim of the present study is to…

We identify and phase a sample of 107 Cepheids with 10<P/days<100 in M81 using the LBT and calibrate their BVI mean magnitudes with archival HST data. The use of a ground-based telescope to identify and phase the Cepheids and HST only for…

The recent SH0ES determination of the Hubble constant, $H_0=73.04\pm1.04$ km/s/Mpc, deviates significantly by $\approx5\sigma$ from the \textit{Planck} value, stimulating discussions on cosmological model extensions. To minimize statistical…

The circumstellar envelopes (CSE) of Cepheids are still not well characterized despite their potential impact on distance determination via both the period-luminosity relation and the parallax-of-pulsation method. This paper aims to…

We examine the multi-wavelength period-luminosity-color relations for Cepheid variables in the Large and Small magellanic Clouds and the Milky Way. From first-principles stellar physics, the luminosity of a Cepheid is determined by its…

The advantages of a near-infrared variant of the Barnes-Evans method for estimating distances to Cepheid variables are described and quantified. A surface brightness-color relation for $K$ photometry and the $(V-K)_0$ color index is…

High-resolution JWST observations can test confusion-limited HST observations for a photometric bias that could affect extragalactic Cepheids and the determination of the Hubble constant. We present JWST NIRCAM observations in two epochs…