Related papers: Improved Color-Temperature Relations and Bolometri…
We present here quantitative diagnostic tools for cool giants that employ low-resolution near-infrared spectroscopy in the $K$-band for stellar population studies. In this study, a total of 260 cool giants (177 stars observed with X-shooter…
We perform a study of 62 solar analog stars to compute their effective temperatures (Teff) using the Balmer line wing fitting procedure and compare them with Teff values obtained using other commonly employed methods. We use observed…
We use MARCS model atmosphere fluxes to compute synthetic colours, bolometric corrections and reddening coefficients for the Hipparcos/Tycho, Pan-STARRS1, SkyMapper and JWST systems. Tables and interpolation subroutines are provided to…
We report progress in the calibration of a method to determine cool dwarf star metallicities using molecular band strength indices. The molecular band index to metallicity relation can be calibrated using chemical abundances calculated from…
Asteroseismology is a powerful tool to precisely determine the evolutionary status and fundamental properties of stars. With the unprecedented precision and nearly continuous photometric data acquired by the NASA Kepler mission, parameters…
The results of a search for cool subdwarfs are presented. Kinematic (U, V, and W) and stellar parameters (Teff, log g, [Fe/H], and V_t) are derived for 134 candidate subdwarfs based on high resolution spectra. The observed stars span 4200K…
A method for determining the effective temperature Teff of G- and K-type giants and supergiants is proposed. The method is based on the use of two photometric indices free from the interstellar absorption influence: the Q index in the UBV…
We use moderate-resolution spectra of nearby late K and M dwarf stars with parallaxes and interferometrically determined radii to refine their effective temperatures, luminosities, and metallicities. We use these revised values to calibrate…
Context: The full spectrum fitting of stellar spectra against a library of empirical spectra is a well-established approach to measure the atmospheric parameters of FGK stars with a high internal consistency. Extending it towards cooler…
We report the first survey of chemical abundances in M and K dwarf stars using atomic absorption lines in high resolution spectra. We have measured Fe and Ti abundances in 35 M and K dwarf stars using equivalent widths measured from (lambda…
Surface brightness-colour relations (SBCRs) are largely used for general studies in stellar astrophysics and for determining extragalactic distances. Based on simulated spectra of late-type stars using MARCS model atmospheres, our aim is to…
A better understanding of the amplitudes of stellar oscillation modes and surface granulation is essential for improving theories of mode physics and the properties of the outer convection zone of solar-like stars. A proper prediction of…
We quantified and calibrated the metallicity and temperature sensitivities of colors derived from nine Wide Field Camera 3 (WFC3) filters aboard the Hubble Space Telescope using Dartmouth isochrones and Kurucz atmospheres models. The…
Estimating precise metallicity of M dwarfs is a well-known difficult problem due to their complex spectra. In this work, we empirically calibrate the metallicity using wide binaries with a F, G, or K dwarf and a M dwarf companion. With 1308…
We derive the stellar parameters of a sample of Galactic early-O type stars by analysing their UV and Far-UV spectra from FUSE (905-1187A), IUE, HST-STIS and ORFEUS (1200-2000A). The data have been modeled with spherical, hydrodynamic,…
We present a new calibration of the Stroemgren metallicity index m1 using red giant (RG) stars in 4 globular clusters (GCs:M92,M13,NGC1851,47Tuc) with metallicity ranging from [Fe/H]=-2.2 to -0.7, marginally affected by reddening…
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…
Various effective temperature scales have been proposed over the years. Despite much work and the high internal precision usually achieved, systematic differences of order 100 K (or more) among various scales are still present. We present…
We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess, $\delta_{0.41}$ defined with $ugr$ data in the SDSS. We estimated the $M_g$ absolute…
We compare high resolution infrared observations of the CO 3-1 bands in the 2.297-2.310 micron region of M dwarfs and one L dwarf with theoretical expectations. We find a good match between the observational and synthetic spectra throughout…