Related papers: A Cepheid is No More: Hubble's Variable 19 in M33
We present the results of our new low-resolution spectroscopic observations of the young compact planetary nebula Hb 12 performed in 2011-2020 with SAI MSU telescopes. We have measured the intensities of more than 50 nebular emission lines…
Over the past several decades, time-series photometry of CSPNe has yielded significant results including, but not limited to, discoveries of nearly 100 binary systems, insights into pulsations and winds in young white dwarfs, and studies of…
Rate of period change $\dot{P}$ for a Cepheid is shown to be a parameter that is capable of indicating the instability strip crossing mode for individual objects, and, in conjunction with light amplitude, likely location within the…
We have started a survey of M 33 in order to find variable stars and Cepheids in particular. We have obtained more than 30 epochs of g'r'i' data with the CFHT and the one-square-degree camera MegaCam. We present first results from this…
A study is presented regarding the nature of several variable stars sampled during a campaign of photometric monitoring from the Abbey Ridge Observatory: 3 eclipsing binaries, 2 semiregulars, a luminous Be star, and a star of uncertain…
The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies characteristic of SPB stars. Seven of these stars also show a few weak, isolated high…
Current measurements of the Hubble constant $H_0$ on scale less than $\sim100$ Mpc appear to be controversial, while the observations made at high redshift seem to provide a relatively low value. On the other hand, the Hubble expansion is…
We report the discovery of a new 13th magnitude variable in Cassiopeia close to the variable KP Cas. Analysis of 6 days of intensive photometry shows a regular, near sinusoidal modulation with an amplitude of 0.024 magnitudes and a period…
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…
The spectral energy distributions (SEDs) of 20 Milky Way (MW), 9 Large Magellanic Cloud (LMC), 7 Small Magellanic Cloud (SMC), 12 M31, and 7 M33 (classical) Cepheids with periods longer than 50 days were constructed using photometric data…
Ultralow amplitude (ULA) and strange mode Cepheids are thought to be pulsating variable stars that are near to or are at the edges of the classical instability strip. Until now, a few dozen such variable star candidates have been found both…
Recently much controversy has been raised about the cosmological conundrum involving the discrepancy in the value of the Hubble constant as implied by Planck satellite observations of the CMBR in the early Universe and that deduced from…
We report the discovery of a surprising binary configuration of the double-mode Cepheid OGLE-LMC-CEP-1347 pulsating in the first (P_1=0.690d) and second overtone (P_2=0.556d) modes. The orbital period (P_orb=59d) of the system is five times…
Concerns are raised regarding the S$H_0$ES results, and the present $H_0$ controversy. The S$H_0$ES $H_0 \simeq 73$ km/s/Mpc has remained relatively unaltered across $18$ years (2005-2023), despite marked shifts in maser and Cepheid…
From our Secret Lives of Cepheids program, the prototype Classical Cepheid, $\delta$ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complements our earlier reported phase-dependent…
We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V =9.1 mag, P~4.9 d) based on almost 600 days of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle…
Local universe measurements of the Hubble constant (H0) using SNe Ia with Cepheids as calibrators yield a value of H0 which is in tension with the value inferred from the CMB and other higher redshift probes. In ref. [1], the authors…
We present the results of the analysis of Type II and anomalous Cepheids using the data from the Kepler K2 mission. The precise light curves of these pulsating variable stars are the key to study the details of their pulsation, such as the…
We develop a statistical method for using multicolor photometry to determine distances using Cepheid variables including the effects of temperature, extinction, and metallicity and apply it to UBVRIJHK photometry of 694 Cepheids in 17…
Based on observations of NGC 300, obtained with the Wide-Field Camera at the 2.2 m ESO/MPI telescope during 29 nights spread over a 5.3 month interval, 117 Cepheids and 12 Cepheid candidates were found which cover the period range from 115…