相关论文: 3D non-LTE iron abundances in FG-type dwarfs

We performed a uniform and detailed analysis of 1112 high-resolution spectra of FGK dwarfs obtained with the HARPS spectrograph at the ESO 3.6 m telescope (La Silla, Chile). Most stars have effective temperatures 4700 K < Teff < 6300 K and…

Stellar abundances, coupled with kinematics are a unique way to understand the chemo-dynamical processes that occurred to build the Milky Way and its local volume as we observe today. However, measuring abundances is challenging as one…

We investigate the effects of horizontal radiative transfer (RT) a NLTE on important diagnostic iron lines in a realistic 3-D HD simulation. Using a multi-level atom we compute and compare widely used Fe I line profiles at 3 different…

We investigate statistical equilibrium of Cr in the atmospheres of late-type stars. The main goal is to ascertain the reason for a systematic abundance discrepancy between Cr I and Cr II lines, which is often encountered in spectroscopic…

M dwarfs are key targets for high-resolution spectroscopic analyses due to a high incidence of these stars in the solar neighbourhood and their importance as exoplanetary hosts. Several methodological challenges make such analyses…

Following our solar work, we perform NLTE calculations of the Mn abundance for fourteen stars with [Fe/H] from 0 to -2.5, mainly to show how NLTE affects Mn abundances in cool stars of different metallicities.The spectrum synthesis and Mn…

We present metallicities derived from a sample of eleven M dwarfs belonging to wide binary systems with warmer FG primary companions observed by the high-resolution (R=22,500) near-infrared SDSS-IV APOGEE spectra. Using a plane-parallel…

We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars, and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples…

In this review we discuss possible systematic errors inherent in classical 1D LTE abundance analyses of late-type stars for the light elements (here: H, He, Li, Be and B). The advent of realistic 3D hydrodynamical model atmospheres and the…

We present non-Local Thermodynamic Equilibrium (non-LTE) calculations for neutral carbon spectral line formation, carried out for a grid of model atmospheres covering the range of late-type stars. The results of our detailed calculations…

We use high quality VLT/UVES published data of the permitted OI triplet and FeII lines to determine oxygen and iron abundances in unevolved (dwarfs, turn-off, subgiants) metal-poor halo stars. The calculations have been performed both in…

We present a grid of computed non-local thermodynamic equilibrium (NLTE) equivalent widths (EW) and NLTE abundance corrections for four Ba II lines: 4554, 5853, 6141, and 6496 A. The grid can be useful in deriving the NLTE barium abundance…

We investigate the feasibility of the Si I infrared (IR) lines as Si abundance indicators for giant stars. We find that Si abundances obtained from the Si I IR lines based on the local thermodynamic equilibrium (LTE) analysis show large…

Hydrodynamical (or 3D) and non-local thermodynamic equilibrium (NLTE) effects are known to affect abundance analyses. However, there are very few observational abundance testsof 3D and NLTE models. We developed a new way of testing the…

We present the analysis of an extensive set of new and literature high quality data concerning Fe, C, N, O, Na, and Mg, exploiting the Teff scale determined in Gratton et al. (1996), and the non-LTE abundance corrections computed in Gratton…

We present the second part of our detailed analysis of the hot sdO and spectroscopic standard star BD+28 4211, in which we focus on the optical spectrum. In the first part of our study, we determined the abundances of some 11 metals…

We present a preliminary local thermodynamic equilibrium (LTE) abundance analysis of the template halo red giant HD122563 based on a realistic, three-dimensional (3D), time-dependent, hydrodynamical model atmosphere of the very metal-poor…

Context. Departures from local thermodynamic equilibrium (LTE) distort the calcium abundance derived from stellar spectra in various ways, depending on the lines used and the stellar atmospheric parameters. The collection of atomic data…

Based on the medium-high resolution (R~ 20,000), modest signal-to-noise ratio (S/N > 70) FLAMES-GIRAFFE spectra, we investigated the copper abundances of 129 red giant branch stars in the Galactic bulge with [Fe/H] from -1.14 to 0.46 dex.…

In the aim of determining accurate iron abundances in stars, this work is meant to empirically calibrate H-collision cross-sections with iron, where no quantum mechanical calculations have been published yet. Thus, a new iron model atom has…