Related papers: Is There a Difference in Luminosity between Field …
A fraction of the extreme horizontal branch stars of globular clusters exhibit a periodic light variability that has been attributed to rotational modulation caused by surface spots. These spots are believed to be connected to inhomogeneous…
Metallicities for six double mode RR Lyrae's (RRd's) in the Large Magellanic Cloud have been estimated using the DeltaS method. The derived [Fe/H] values are in the range [Fe/H] = -1.09 to -1.78 (or -0.95 to -1.58, adopting a different…
We present a new study of the variable star population in globular cluster 5 of the Fornax dwarf spheroidal galaxy, based on B and V time series photometry obtained with the MagIC camera of the 6.5 m Magellan Clay telescope and…
RR~Lyrae variables are widely used tracers of Galactic halo structure and kinematics, but they can also serve to constrain the distribution of the old stellar population in the Galactic bulge. With the aim of improving their near-infrared…
RR Lyrae stars have long been popular standard candles, but significant advances in methodology and technology have been made in recent years to increase their precision as distance indicators. We present multi-wavelength (optical…
We investigate the variation of galaxy clustering with luminosity using the recently completed SSRS2 sample. Clustering measurements based on the two-point correlation function and the variance of counts in cells reveal the existence of a…
A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main sequence stars with spectral types from solar to A0 show predictable…
We present GALEX near ultraviolet (NUV:1750 - 2750A) and far ultraviolet (FUV: 1350 - 1750A) imaging observations of two 1.2 degree diameter fields in the Hyades and Pleiades open clusters in order to detect possible UV variability of the…
I review statistical parallax absolute magnitude determinations which employ data from the HIPPARCOS satellite for RR Lyrae and Cepheid variables, and for several other stellar classes. Five groups have studied the RR Lyrae stars, and the…
A high percentage of the astrophysically important RR Lyrae stars show a periodic amplitude and/or phase modulation of their pulsation cycles. More than a century after its discovery, this "Blazhko effect" still lacks acceptable theoretical…
We briefly review our photometric and spectroscopic study of RR Lyrae variable stars in the bar of the Large Magellanic Cloud (LMC), that allowed us to reconcile the so-called "short" and "long" distance moduli of the LMC on the value…
We review the results on distances and absolute ages of galactic globular clusters (GCs) obtained after the release of the Hipparcos catalogue. Several methods for the Population II local distance scale are discussed, exploiting NEW RESULTS…
The goal of this paper is to characterise the light variation properties of Mira variables in the Small Magellanic Cloud. We have investigated a combined optical and near infrared multi-epoch dataset of Mira variables based on our…
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…
We present a comprehensive photometric study of RR Lyrae stars in the M3 globular cluster, utilising a vast dataset of 3140 optical ($UBVRI$) CCD images spanning 35 years from astronomical data archives. We have successfully identified…
We have observed the galaxy environments around two complete samples of radio-loud (steep-spectrum) and radio-quiet quasars (RLQ and RQQ) at 0.5 < z < 0.8 that are matched in B-luminosity, and find that the environments of both quasar…
We present Hubble Space Telescope observations taken with the Advanced Camera for Surveys Wide Field Channel of two fields near M32 - between four and six kpc from the center of M31. The data cover a time baseline sufficient for the…
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…
We present measurements of the periods, amplitudes, and types of 74 RR Lyrae stars in the globular cluster M15 derived from Nickel 1 m telescope observations conducted at LickObservatory in 2019 and 2020. Of these RR Lyrae stars, two were…
Cepheids and RR Lyrae stars are important pulsating variable stars in distance scale work because they serve as standard candles. Cepheids follow well-defined period-luminosity (PL) relations defined for bands extending from optical to…