Related papers: Empirically Constrained Color-Temperature Relation…
We have been using Keck laser guide star adaptive optics to monitor the orbits of ultracool binaries, providing dynamical masses at lower luminosities and temperatures than previously available and enabling strong tests of theoretical…
Buzzoni's (1989) grid of synthetic spectral energy distributions, representative of old stellar populations, was used to derive colours in different photometric systems, and to compare the theoretical predictions with the observational data…
We carry out and analyze new multi-color photometry of the Galactic globular cluster (GC) M75 in UBVI and focus on the brighter sequences of the color- magnitude diagram (CMD), with particular emphasis on their location in U-based CMD.…
A new intrinsic-colour calibration ($(b$--$y)_{o}$--$\beta$) is presented for the $uvby$--$\beta$ photometric system, making use of re-calibrated Hipparcos parallaxes and published reddening maps. This new calibration for…
In the quest for the formation and evolution of galaxy clusters, Rakos and co-workers introduced a spectrophotometric method using the modified Str\"omgren photometry. But with the considerable debate toward the project's abilities, we…
We present interferometric diameter measurements of 21 K- and M- dwarfs made with the CHARA Array. This sample is enhanced by literature radii measurements to form a data set of 33 K-M dwarfs with diameters measured to better than 5%. For…
CCD photometry on the uvbyCaHbeta system is presented for the open cluster, NGC 3680. Restricting the data to probable cluster members using the CMD and the photometric indices alone defines a sample of 34 stars at the cluster turnoff that…
Extremely large telescopes (ELTs) provide an opportunity to observe surface inhomogeneities for ultracool objects including M dwarfs, brown dwarfs (BDs), and gas giant planets via Doppler imaging and spectro-photometry techniques. These…
We derive an empirical effective temperature and bolometric luminosity calibration for G and K dwarfs, by applying our own implementation of the InfraRed Flux Method to multi-band photometry. Our study is based on 104 stars for which we…
Our knowledge about unresolved stellar systems comes from comparing integrated-light properties to SSP models. Therefore it is crucial to calibrate the latter as well as possible by integrated-light colors of clusters that have reliable…
Context. Chromospheric fibrils are thin and elongated structures that connect nearby photospheric magnetic field concentrations of opposite polarities. Aims. We assess the possibilities and drawbacks related to the use of current…
Reported are UBV and uvbybeta observations of 15 candidates for Kepler primary astero- seismic targets and 14 other stars in the Kepler field, carried out at the M.G. Fracastoro station of the Catania Astrophysical Observatory. These data…
We examine the emergent fluxes from helium-core white dwarfs following their evolution from the end of pre-white dwarf stages down to advanced cooling stages. For this purpose, we include a detailed treatment of the physics of the…
We present synthetic broad-band photometric colors of a late-type giant located close to the RGB tip (T_eff = 3640 K, log g = 1.0 and [M/H] = 0.0). Johnson-Cousins-Glass BVRIJHK colors were obtained from the spectral energy distributions…
A new calibration of the Stroemgren (b-y),m_1 diagram in terms of iron abundance of red giants is presented. This calibration is based on a homogeneous sample of giants in the globular clusters omega Centauri, M22, and M55 as well as field…
Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs, but is within reach for only a limited sample of nearby, bright stars. We use interferometrically-measured radii, bolometric luminosities,…
We describe a near-IR photometric search for cool red dwarf companions to hot EUV-detected white dwarfs (WDs). While some composite systems have been found optically among WDs detected in recent EUV All-Sky Surveys, we develop an IR…
Empirical correlations between stellar parameters such as rotation or radius and magnetic activity diagnostics require estimates of the effective temperatures and the stellar radii. The aim of this study is to propose simple methods that…
We present an improved uvby-metallicity relation calibrated for F, G, and early K dwarfs, and an analogous uvby-T(eff) relation, both derived using a Levenberg-Marquardt minimization scheme. Our calibrations are based on 1533 stars which…
The development of powerful infrared observational technics enables the study of very extincted objects and young embedded star forming regions. This is especially interesting in the context of massive stars which form and spend a non…