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We present an evaluative study of some current methods utilized in the analysis of infrared (IR) observatinons of star-forming regions. A series of self-consistent radiative transfer models are constructed, with the outputs analysed using…
We report the statistical properties of stars and brown dwarfs obtained from three radiation hydrodynamical simulations of star cluster formation with metallicities of 1, 1/10 and 1/100 of the solar value. The star-forming clouds are…
We have entered an era of large spectroscopic surveys in which we can measure, through automated pipelines, the atmospheric parameters and chemical abundances for large numbers of stars. Calibrating these survey pipelines using a set of…
We analyze a sample of tens of thousands of spectra of halo turnoff stars, obtained with the optical spectrographs of the Sloan Digital Sky Survey (SDSS), to characterize the stellar halo population "in situ" out to a distance of a few tens…
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…
Extensive photoionization model grids are computed for single star HII regions using stellar atmosphere models from the WM-basic code. Mid-IR emission line intensities are predicted and diagnostic diagrams of [NeIII]/[NeII] and [SIV]/[SIII]…
Context. Spectroscopic surveys like APOGEE, GALAH, and LAMOST have significantly advanced our understanding of the Milky Way by providing extensive stellar parameters and chemical abundances. Complementing these, photometric surveys with…
We present measurements of [Fe/H] for six M supergiant stars and three giant stars within 0.5 pc of the Galactic Center (GC) and one M supergiant star within 30 pc of the GC. The results are based on high-resolution (lambda / Delta lambda…
To analyse stellar populations in galaxies a widely used method is to apply theoretically derived responses of stellar spectra and line indices to element abundance variations, hereafter referred to as response functions. These are applied…
The estimation of stellar atmospheric parameters for large-scale samples, particularly metal-poor stars, is a cornerstone of Galactic archaeology. In this work, we optimized a photometric filter design tailored to measuring stellar…
Stellar spectra derived from current multiple-object fiber-fed spectroscopic radial-velocity surveys, of the type feasible with, among other examples, AUTOFIB, 2dF, HYDRA, NESSIE, and the Sloan survey, differ significantly from those…
We checked consistency between the copper abundance derived in six metal-poor stars using UV Cu II lines (which are assumed to form in LTE) and UV Cu I lines (treated in NLTE). Our program stars cover the atmosphere parameters which are…
At $z=1-3$, the formation of new stars is dominated by dusty galaxies whose far-IR emission indicates they contain colder dust than local galaxies of a similar luminosity. We explore the reasons for the evolving IR emission of similar…
We have undertaken a spectroscopic survey of field stars to find metal-poor objects among them. Observations are carried out using OMR spectrograph attached to 2.3m telescope at VBO Kavalur, India. The sample of candidate stars are chosen…
Modern large-scale photometric surveys have provided us with multi-band photometries of billions of stars. Determining the stellar atmospheric parameters, such as the effective temperature (\teff) and metallicities (\feh), absolute…
A non-LTE analysis of C I lines at 1.068-1.069 micron was carried out for selected 46 halo/disk stars covering a wide metallicity range (-3.7 <[Fe/H]< +0.3), based on the spectral data collected with IRCS+AO188 of the Subaru Telescope, in…
We present the results of an abundance analysis for a sample of stars with $-4<$[Fe/H]$<-2$. The data were obtained with the HIRES spectrograph at Keck Observatory. The set includes 28 stars, with effective temperature ranging from 4800 to…
Molecular line observations of starless (prestellar) cores combined with a chemical evolution modeling and radiative transfer calculations are a powerful tool to study the earliest stages of star formation. However, conclusions drawn from…
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…
We present the first results from MMT and Keck spectroscopy for a large sample of $0.1\leq z\leq1$ emission-line galaxies selected from our narrow-band imaging in the Subaru Deep Field. We measured the weak [OIII]$\lambda$4363 emission line…