相关论文: Molecular bands in extremely metal-poor stars. Gra…
Molecular features such as the G-band, CN-band and NH-band are important diagnostics for measuring a star's carbon and nitrogen abundances, especially in metal-poor stars where atomic lines are no longer visible in stellar spectra. Unlike…
The new generation of 3D hydrodynamical model atmospheres have been employed to study the impact of a realistic treatment of stellar convection on element abundance determinations of globular cluster stars for a range of atomic and…
We make use of three dimensional hydrodynamical simulations to investigate the effects of granulation on the Cu I lines of Mult. 1 in the near UV, at 324.7 nm and 327.3 nm. These lines remain strong even at very low metallicity and provide…
To constrain the properties of the first stars with the chemical abundance patterns observed in metal-poor stars, one must identify any non-trivial effects that the hydrodynamics of metal dispersal can imprint on the abundances. We use…
I present here the main results of recent realistic, 3D, hydrodynamical simulations of convection at the surface of metal-poor red giant stars. I discuss the application of these convection simulations as time-dependent, 3D, hydrodynamical…
We investigate the influence of convection on the formation of molecular spectral lines in the atmospheres of late-type giants. For this purpose we use the 3D hydrodynamical CO5BOLD and classical 1D LHD stellar atmosphere codes and…
Context. Tighter constraints on metal-poor stars we observe are needed to better understand the chemical processes of the early Universe. Computing a stellar spectrum in 3D allows one to model complex stellar behaviours, which cannot be…
We present a detailed analysis of the carbon and nitrogen abundances of two dwarf carbon-enhanced metal-poor (CEMP) stars: SDSS J1349-0229 and SDSS J0912+0216. We also report the oxygen abundance of SDSS J1349-0229. These stars are…
Binary molecules such as CO, OH, CH, CN, and C$_2$ are often used as abundance indicators in stars. These species are usually assumed to be formed in chemical equilibrium. The time-dependent effects of hydrodynamics can affect the formation…
We review the theory behind abundance of experimentally observed nanoclusters produced in beams, aiming to understand their magic number behavior. It is shown how use of statistical physics, with certain assumptions, reduces the calculation…
Understanding the gas abundance distribution is essential when tracing star formation using molecular line observations. Changing density and temperature conditions cause gas to freeze-out onto dust grains, and this needs to be taken into…
We utilize state-of-the-art 3D hydrodynamical and classical 1D stellar model atmospheres to study the influence of convection on the formation properties of various atomic and molecular spectral lines in the atmospheres of four red giant…
Simultaneous analysis of the C_2 and CN molecular bands in the 5100-5200 and 7930-8100A spectral regions is a promising alternative for the accurate determination of the carbon (C) and nitrogen (N) abundance in the atmospheres of the…
In this work we have used 3D hydrodynamical (CO5BOLD) and 1D hydrostatic (LHD) stellar atmosphere models to study the importance of convection and horizontal temperature inhomogeneities in stellar abundance work related to late-type giants.…
A major limitation and a continuing source of confusion in the interpretation of molecular line observations has been the large degree of chemical complexity that is observed in star-forming molecular cores. The past decade has seen…
Based on high-resolution spectral observations for a sample of very metal-poor stars, we investigate how well stellar chemical abundances can be derived with available theoretical methods and computational tools.
Recent developments in the three-dimensional (3D) spectral synthesis code Linfor3D have meant that, for the first time, large spectral wavelength regions, such as molecular bands, can be synthesised with it in a short amount of time. A…
The characteristics of the stellar populations in the Galactic Bulge inform and constrain the Milky Way's formation and evolution. The metal-poor population is particularly important in light of cosmological simulations, which predict that…
We study the formation of the photonic band structure in small clusters of dielectric spheres. The first signs of the band structure, an attribute of an infinite crystal, can appear for clusters of 5 particles. Density of resonant states of…
Recent observations of globular clusters (GCs) suggest that elemental abundance variations may exist between first-generation (1G) stars. We propose that metal abundance ('metallicity') spreads within GC forming giant molecular clouds…