Related papers: Metal-Poor Stars
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…
We study star formation history and stellar metallicity distribution in galaxies in a Lambda cold dark matter universe using a hydrodynamic cosmological simulation. Our model predicts star formation rate declining in time exponentially from…
We report on early results from a pilot program searching for metal-poor stars with LAMOST and follow-up high-resolution observation acquired with the MIKE spectrograph attached to the Magellan~II telescope. We performed detailed abundance…
The question how much star formation is occurring at low metallicity throughout the cosmic history appears crucial for the discussion of the origin of various energetic transients, and possibly - double black hole mergers. We revisit the…
In this PhD thesis we investigate stellar evolution and nucleosynthesis in the low- and extremely-low metallicity regime - including models of stars with a pure Big Bang composition (i.e. $\rm{Z} = 0$). The metallicity range of the…
We present initial results measuring the companion fraction of metal-poor stars ([Fe/H]$<-$2.0). We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects. The binary fraction…
The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide…
Various nucleosynthesis studies have pointed out that the r-process elements in very metal-poor (VMP) halo stars might have different origins. By means of familiar concepts from statistics (correlations, cluster analysis, rank tests of…
Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that…
The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few…
The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium1, almost all other elements were created in stars and supernovae. The mass fraction, Z, of elements more massive than helium, is called…
The chemical fingerprints of the first stars are retained within the photospheres of ancient unevolved metal-poor stars. A significant fraction of these stellar fossils is represented by stars known as Carbon-Enhanced Metal-Poor (CEMP),…
An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as their iron abundance, [Fe/H], decreases below [Fe/H] = -2.0. The CEMP-s stars have the highest absolute carbon abundances, [C/H], and are thought to owe their…
Elements heavier than hydrogen and helium, collectively termed metals, were created inside stars and dispersed through space at the final stages of stellar evolution. The relative amounts of different isotopes (variants of the same element…
The earliest assembly of the Milky Way remains poorly understood, yet the spatial, chemical, and kinematic properties of its most metal-poor stars provide a unique fossil record of its proto-Galaxy phase. Understanding how this ancient…
The first generation of stars, often called Population III (or Pop III), form from metal-free primordial gas at redshifts 30 and below. They dominate the cosmic star formation history until redshifts 15 to 20, at which point the formation…
We present the three-dimensional orbital motions of metal-poor stars in conjunction with their metal abundances, for the purpose of getting insight into the formation process of the Galaxy. Our sample stars, which include metal-deficient…
The nucleosynthesis in the first massive stars may be constrained by observing the surface composition of long-lived very iron-poor stars born around 10 billion years ago from material enriched by their ejecta. Many interesting clues on…
The redshifted ultraviolet light from early stars at z ~ 10 contributes to the cosmic near infrared background. We present detailed calculations of its spectrum with various assumptions about metallicity and mass spectrum of early stars. We…
The star formation history of a given population remains imprinted in the chemical distributions of the their individuals. The parallel study of stellar abundances and nucleosynthesis helps to understand the production of the elements…