Results 11 to 20 of about 226,393 (319)

Chemical Abundances from the Continuum [PDF]

Physica Scripta, 2008
The calculation of solar absolute fluxes in the near-UV is revisited, discussing in some detail recent updates in theoretical calculations of bound-free opacity from metals.
Allende Prieto C, Allende Prieto C, Allende Prieto C, Asplund M, Bautista M A, C Allende Prieto, Cunto W, Hubeny I Lanz T, Koesterke L, Nahar S N, Sbordone L   +10 more
core   +2 more sources

Chemical Abundances of Planetary Nebulae in M33 [PDF]

Astronomy & Astrophysics, 2004
Using spectroscopic data presented in Magrini et al. (2003), we have analyzed with the photoionization code CLOUDY 94.00 (Ferland et al. 1998) 11 Planetary Nebulae belonging to the spiral galaxy M 33. Central star temperatures and nebular parameters have
A. Mampaso, Ambartsumian, Armsdorfer, Che, Corradi, Costa, Dufour, Exter, Ferland, Gurzadyan, Henry, Howard, Iben, Jacoby, Jacoby, Jacoby, Kingsburgh, L. Magrini, Leisy, M. Perinotto, Magrini, Mampaso, Maran, Morisset, Peimbert, Perinotto, Phillips, R. L. M. Corradi, Rauch, Richer, Stasinska, Vílchez, Walsh, Walsh   +33 more
core   +2 more sources

Chemical abundances in Seyfert galaxies – VIII. Argon abundance estimates [PDF]

Monthly Notices of the Royal Astronomical Society, 2021
ABSTRACT For the first time, the argon abundance relative to hydrogen abundance (Ar/H) in the narrow line region of a sample of Seyfert 2 nuclei has been derived. In view of this, optical narrow emission line intensities of a sample of 64 local Seyfert 2 nuclei (z < 0.25) taken from Sloan Digital Sky Survey DR7 and measured by the
A F Monteiro, O L Dors
  +12 more sources

Chemical abundances in active galaxies [PDF]

Monthly Notices of the Royal Astronomical Society, 2020
ABSTRACT The Sloan Digital Sky Survey (SDSS) has proved to be a powerful resource for understanding the physical properties and chemical composition of star-forming galaxies in the local Universe. The SDSS population of active galactic nuclei (AGNs) remains as of yet less explored in this capacity.
Flury, Sophia R., Moran, Edward C.
openaire   +2 more sources

High-precision chemical abundances of Galactic building blocks. The distinct chemical abundance sequence of Sequoia

Astronomy & Astrophysics, 2021
Context. Sequoia is a retrograde kinematic substructure in the nearby Galactic halo, whose properties are a matter of debate. For example, previous studies do not necessarily agree on the chemical abundances of Sequoia stars, which are important for understanding its nature. Aims.
Tadafumi Matsuno, Helmer H. Koppelman, A. Helmi, Wako Aoki, Miho N. Ishigaki, Takuma Suda, Zhen Yuan, Kohei Hattori   +7 more
openalex   +4 more sources

Chemical abundances in Seyfert galaxies – X. Sulphur abundance estimates

Monthly Notices of the Royal Astronomical Society, 2023
ABSTRACT For the first time, the sulphur abundance relative to hydrogen (S/H) in the narrow-line regions of a sample of Seyfert 2 nuclei (Sy 2s) has been derived via direct estimation of the electron temperature. Narrow emission-line intensities from the Sloan Digital Sky Survey (SDSS) Data Release 17 (DR17) [in the wavelength range 3000
Oli L Dors, M Valerdi, R A Riffel, R Riffel, M V Cardaci, G F Hägele, Mark Armah, M Revalski, S R Flury, P Freitas-Lemes, E B Amôres, A C Krabbe, L Binette, A Feltre, T Storchi-Bergmann   +14 more
openaire   +3 more sources

Origin of cosmic chemical abundances [PDF]

Monthly Notices of the Royal Astronomical Society, 2015
Cosmological N-body hydrodynamic computations following atomic and molecular chemistry (e$^-$, H, H$^+$, H$^-$, He, He$^+$, He$^{++}$, D, D$^+$, H$_2$, H$_2^+$, HD, HeH$^+$), gas cooling, star formation and production of heavy elements (C, N, O, Ne, Mg, Si, S, Ca, Fe, etc.) from stars covering a range of mass and metallicity are used to explore the ...
Maio, Umberto, Tescari, Edoardo
openaire   +2 more sources

Precision Chemical Abundance Measurements [PDF]

Proceedings of the International Astronomical Union, 2012
AbstractThis talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios.
Yong, David, Grundahl, Frank, Meléndez, Jorge, Norris, John E.   +3 more
openaire   +2 more sources

Chemical Evolution of CNO Abundances [PDF]

, 2003
New low and intermediate star yields calculated by Buell (1997) are evaluated by using them in a Galactic Chemical Evolution model.
Gavilan, M., Molla, M.
openaire   +2 more sources

Stellar evolution with SMC chemical abundances [PDF]

International Astronomical Union Colloquium, 1981
Evolutionary computations are presented for massive stars between 20 Mo and 100 Mo with chemical abundances holding for the Small Magellanic Cloud, i.e. X = .76 and Z = .003. Mass loss by stellar wind is taken into account during core hydrogen burning.
P. Hellings, D. Vanbeveren
openaire   +1 more source