Related papers: Stellar Diameters and Temperatures II. Main Sequen…
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…
(Abridged) Low-mass stars have been recognised as promising targets in the search for rocky, small planets with the potential of supporting life. Doppler search programmes using high-resolution spectrographs like HARPS or HARPS-N are…
We present a spectroscopic and photometric calibration to derive effective temperatures $T_{\mathrm{eff}}$ and metallicities [Fe/H] for M dwarfs, based on a Principal Component Analysis of 147 spectral indices measured off moderate…
We report on 13 new high-precision measurements of stellar diameters for low-mass dwarfs obtained by means of near-infrared long-baseline interferometry with PIONIER at the Very Large Telescope Interferometer. Together with accurate…
Precise and accurate parameters for late-type (late K and M) dwarf stars are important for characterization of any orbiting planets, but such determinations have been hampered by these stars' complex spectra and dissimilarity to the Sun. We…
Aims. In this work we develop a technique to obtain high precision determinations of both metallicity and effective temperature of M dwarfs in the optical. Methods. A new method is presented that makes use of the information of 4104 lines…
Large numbers of low-to-medium resolution spectra of M-type dwarf stars from both the local Galactic disk and halo are available from various surveys. In order to fully exploit these data, we develop a template-fit method using a set of…
We investigated almost 500 stars distributed among 193 binary or multiple systems made of late-F, G-, or early-K primaries and late-K or M dwarf companion candidates. For all of them, we compiled or measured coordinates, J-band magnitudes,…
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…
We present here medium resolution (\lambda /\Delta\lambda\sim1200) H- and K-band spectra of M type dwarf stars covering the wavelength range 1.50 - 1.80 {\mu}m and 1.95 - 2.45 {\mu}m. The sample includes 53 dwarf stars (M0V-M7V) from new…
Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main- sequence stars, ranging from spectral type A7 to K0, five of which are exoplanet host stars. We derive linear radii, effective temperatures, and…
Deriving metallicities for solar-like stars follows well-established methods, but for cooler stars such as M dwarfs, the determination is much more complicated due to forests of molecular lines that are present. Several methods have been…
Context. Being the most numerous and oldest stars in the galaxy, M dwarfs are objects of great interest for exoplanet searches. The presence of molecules in their atmosphere complicates our understanding of their atmospheric properties. But…
The ability to perform detailed chemical analysis of Sun-like F-, G-, and K-type stars is a powerful tool with many applications including studying the chemical evolution of the Galaxy and constraining planet formation theories.…
M subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal poor stars, hydrostatic equilibrium is reached at a smaller radius, leading…
We estimate effective temperature ($T_{\rm eff}$), stellar radius, and luminosity for a sample of 271 M-dwarf stars (M0V-M7V) observed as a part of CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared…
The temperatures and colors of stellar models are much less secure than predicted luminosities; consequently, it is important to ensure that the models which are used to interpret data for stellar populations satisfy existing observational…
Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of…
With the existing and upcoming large multi-fibre low-resolution spectrographs, the question arises how precise stellar parameters such as Teff and [Fe/H] can be obtained from low-resolution K-band spectra with respect to traditional…
The effective temperature (Teff) of the radiation field of the ionizing star(s) of a large sample of extragalactic HII regions was estimated using the R= log([OII](3727)/[OIII]5007) index. We used a grid of photoionization models to…