Related papers: RRAB Variables and Metallicity

Since 1999, a radial velocity survey of 179 red giant stars is ongoing at Lick Observatory with a one month cadence. At present ~20-100 measurements have been collected per star with an accuracy of 5 to 8 m/s. Of the stars monitored, 145…

We adopted the procedure of Carney to obtain a metallicity calibration for dwarfs for the RGU-photometry. For this purpose we selected 76 dwarfs of different metallicities from Carney, and Strobel et al., and evaluated their \delta(U-G)…

The rapidly oscillating Ap (roAp) stars exhibit pulsational photometric and/or radial velocity variations on time scales of several minutes, which are essential to test current pulsation models as well as our assumptions of atmospheric…

In this paper, we report the detections of stellar variabilities from the first 2-year observations of sky area of about 1300 square degrees from the Tsinghua University-NAOC Transient Survey (TNTS). A total of 1237 variable stars…

The observational data of the near infrared bands (H and K) have been used for the modeling mean light curves. Also the visual observational data have been fitted the same. The infrared and visual mean light curves were compared. All…

Metallicity ($Z$) estimates based on ultraviolet (UV) emission lines from the narrow-line regions (NLRs) of active galactic nuclei (AGNs) have been found to differ from those derived from optical lines. However, the origin of this…

The metallicity is a critical parameter that affects the correct determination fundamental characteristics stellar cluster and has important implications in Galactic and Stellar evolution research. Fewer than 10 % of the 2174 currently…

RR Lyrae stars are useful chemical tracers thanks to the empirical relationship between their heavy-element abundance and the shape of their light curves. However, the consistent and accurate calibration of this relation across multiple…

Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude delta Scuti star) located in the field-of-view of the Kepler…

Context. Luminous blue variables (LBVs) are rare massive stars with very high luminosity. They are characterized by strong photo-metric and spectroscopic variability related to transient eruptions. The mechanisms at the origin of these…

We present a detailed abundance analysis and atmospheric parameters of 76 stars from a survey to identify field Galactic red horizontal-branch (RHB) stars. High-resolution echelle spectra (R\simeq60,000, S/N>=100) were obtained with 2.7 m…

Evidence for the existence of Mira Period-Luminosity relations is reviewed including recent work on Miras with thick circumstellar shells. The calibration of the relation at K is discussed in detail. The nature of variables deviating from…

Understanding how the magnetic activity of low-mass stars depends on their fundamental parameters is an important goal of stellar astrophysics. Previous studies show that activity levels are largely determined by the stellar Rossby number…

Str\"omgren $uvby-\beta$ photometry of the stars classified as RR Lyrae stars RU Piscium, SS Piscium and TU Ursae Majoris has been used to estimate their iron abundance, temperature, gravity and absolute magnitude. The stability of the…

In this study, we conduct a comparative analysis of the properties of Blazhko and non-Blazhko RRab stars. We identified 1054 non-Blazhko and 785 Blazhko RRab stars in the photometric data observed by K2 mission, which, combined with those…

We present our analysis of a large sample (over 150k) of candidate Galactic RR Lyrae (RRL) stars for which we derived high quality photometry at UV, optical and infrared wavelengths, using data from publicly available surveys. For a…

Context. The third Gaia Data Release, which includes BP/RP spectra for 219 million sources, has opened a new window in the exploration of the chemical history and evolution of the Milky Way. The wealth of information encapsulated in these…

We present new time-series CCD \emph{VR} photometry of the globular cluster NGC 5634. We aim to use the known RR Lyrae stars, members of the cluster, as indicators of mean metallicity and distance. Accurate coordinates, periods and an…

Accurate metallicities of RR Lyrae are extremely important in constraining period-luminosity-metallicity relationships (PLZ), particularly in the near-infrared. We analyse 69 high-resolution spectra of Galactic RR Lyrae stars from the…

We present the detailed spectroscopic analysis of 72 evolved stars, including the [Fe/H] determination for the whole sample. These metallicities, together with the Teff values and the absolute V magnitude derived from Hipparcos parallaxes,…