Related papers: Empirically Constrained Color-Temperature Relation…

New Johnson-Cousins UBVRI photometry of giants in globular clusters is combined with JHK photometry on the CIT system to produce color sequences for giants from the globular clusters M3, M5, M13, and M92. UBVRI data are also presented for…

CCD photometry of the intermediate-age open cluster, IC 4651, on the uvbyHbeta system is presented and analyzed. By using a combination of the information from the color-magnitude diagram (CMD) and the color-color diagrams, a sample of 98…

(Abridged) We investigate the effects of metallicity on the broad-band photometric colors of late-type giants, and make a comparison of synthetic colors with observed photometric properties of late-type giants over a wide range of effective…

We present an analysis of the intrinsic colors and temperatures of 5-30 Myr old pre-main sequence (pre-MS) stars using the F0 through M9 type members of nearby, negligibly reddened groups: Eta Cha cluster, TW Hydra Association, Beta Pic…

In the present work we compare in detail some of the major theoretical libraries with observations, aiming at detecting weaknesses and strengths from the stellar population modelling point of view. We compared model predictions and…

We present deep CCD photometry of the globular cluster M13 (NGC 6205) in the Stromgren uvby-Beta system, and determine a foreground reddening of E(b-y)= 0.015mag. From a fit to the main-sequence of metal-poor subdwarfs with Hipparcos…

We present a new technique to determine age and metallicity of old stellar populations (globular clusters and elliptical galaxies) using an iterative principal component analysis on narrow band (Str\"omgren) colors. Our technique is capable…

A new all-sky catalogue of all available uvbybeta measurements from the literature was generated. The uvbybeta photometric system is widely used for the study of various Galactic and extragalactic objects. It measures the colour due to…

Stellar evolutionary tracks for $0.12 \le M/M_\odot \le 1.0$ have been computed for each of several variations in the abundances of C, N, and O, assuming mass-fraction helium abundances $Y = 0.25$ and $0.29$, and 11 metallicities in the…

Spectrophotometric indices for $18$ Galactic globular clusters, obtained from CCD observations and careful reductions, were used to determine reliable calibrations on metallicity $[Fe/H]$. The indices were measured in the bandpasses adopted…

Victoria-Regina isochrones for $-0.4 \le$ [alpha/Fe] $\le +0.4$ and a wide range in [Fe/H], along with complementary zero-age horizontal branch (ZAHB) loci, have been applied to the color-magnitude diagram (CMD) of Carina. The color…

I use HST spectrophotometry to analyze the calibration of 3 optical photometry systems: Tycho-2 B_T V_T, Str\"omgren u v b y, and Johnson U B V. For Tycho-2, I revisit the analysis of Ma\'iz Apell\'aniz (2005) to include the new…

Although stellar SED models are constantly improving and seem to show similar differential tendencies as measured spectra, their absolute properties (eg. absolute flux in different wavelength regions) can still differ significantly from the…

As part of a project to model the integrated spectra and colors of elliptical galaxies through evolutionary synthesis, we have refined our synthetic spectrum calculations of M giants. After critically assessing three effective temperature…

We performed a new calibration of the Stroemgren metallicity index m1 based on the b-y color of cluster red giant stars. The current Metallicity-Index-Color relation is not linear in the color range 0.40 < b-y < 1.0, but provides iron…

Intermediate-band photometry of the Hyades cluster on the Caby system is presented for dwarf stars ranging from spectral type A through late K. A mean hk, b-y relation is constructed using only single stars without anomalous atmospheres and…

We present new Stromgren and Washington data sets for the Bootes I dwarf galaxy, and combine them with the available SDSS photometry. The goal of this project is to refine a ground-based, practical, accurate method to determine age and…

Based on a simple thermodynamical argument, we proposed a unified cloudy model (UCM) with a warm dust cloud deep in the photosphere. We showed, for the first time, that a single grid of model photospheres (Teff between 800 and 2600K) offers…

We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use SDSS griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature…

We report results that show that the straightforwardly star cluster metallicities obtained from Str\"omgren $vby$ photometry is age-dependent and need to be corrected for further use. This outcome arises from the comparison of [Fe/H] values…