Results 31 to 40 of about 4,406,721 (399)

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
openaire   +3 more sources

Chemical Abundances along the 1G Sequence of the Chromosome Maps: The Globular Cluster NGC 3201 [PDF]

Astrophysical Journal, 2019
The Hubble Space Telescope (HST) UV Legacy Survey of Galactic Globular Clusters (GCs) has investigated multiple stellar populations by means of the “chromosome map” (ChM) diagnostic tool that maximizes the separation between stars with different chemical
Anna F. Marino, A. Milone, A. Sills, David Yong, A. Renzini, L. Bedin, G. Cordoni, F. D’Antona, H. Jerjen, A. Karakas, E. Lagioia, G. Piotto, M. Tailo   +12 more
semanticscholar   +1 more source

Observing the signatures of AGB s-process nucleosynthesis in planetary nebulae: An origins story

Frontiers in Astronomy and Space Sciences, 2022
I relate an anecdotal history of the beginnings of a new initiative in studies of the chemical composition of planetary nebulae: namely, investigating abundances of elements beyond the iron-peak through infrared spectroscopy.
Harriet L. Dinerstein
doaj   +1 more source

Chemical Abundances in a Turbulent Medium–H2, OH+, H2O+, ArH+ [PDF]

Astrophysical Journal, 2019
Supersonic turbulence results in strong density fluctuations in the interstellar medium (ISM), which have a profound effect on the chemical structure. Particularly useful probes of the diffuse ISM are the ArH+, OH+, H2O+ molecular ions, which are highly ...
S. Bialy, D. Neufeld, M. Wolfire, A. Sternberg, B. Burkhart   +4 more
semanticscholar   +1 more source

The Open Cluster Chemical Abundances and Mapping Survey. II. Precision Cluster Abundances for APOGEE Using SDSS DR14 [PDF]

Astronomical Journal, 2018
The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to produce a comprehensive, uniform, infrared-based spectroscopic data set for hundreds of open clusters, and to constrain key Galactic dynamical and chemical parameters from this ...
J. Donor, P. Frinchaboy, K. Cunha, B. Thompson, J. O’Connell, G. Zasowski, K. Jackson, B. McGrath, B. McGrath, Andres Almeida, D. Bizyaev, D. Bizyaev, R. Carrera, D. A. García-Hernández, C. Nitschelm, K. Pan, O. Zamora   +16 more
semanticscholar   +1 more source

Chemical Tracing and the Origin of Carbon in the Galactic Disk

Universe, 2022
A basic problem in studies of the evolution of chemical elements in galaxies is the uncertainties in the yields of elements produced by different types of stars.
Bengt Gustafsson
doaj   +1 more source

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   +3 more sources

Chemical Evolution of the Galactic Bulge as Derived from High-Resolution Infrared Spectroscopy of K and M Red Giants [PDF]

, 2006
We present chemical abundances in K and M red-giant members of the Galactic bulge derived from high-resolution infrared spectra obtained with the Phoenix spectrograph on Gemini-South.
Bessel M. S., Costes M., Edvardsson B., Gratton R. G., Gustafsson B., Katia Cunha, Nissen P. E., Plez B., Udalski A., Udalski A., Verne V. Smith   +10 more
core   +3 more sources

Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. I. Signatures of Diffusion in the Open Cluster M67 [PDF]

, 2018
Detailed chemical abundance distributions for 14 elements are derived for eight high-probability stellar members of the solar metallicity old open cluster M67 with an age of ∼4 Gyr.
D. Souto, K. Cunha, V. Smith, C. Prieto, C. Prieto, D. A. García-Hernández, D. A. García-Hernández, M. Pinsonneault, Parker H. Holzer, P. Frinchaboy, J. Holtzman, J. A. Johnson, H. Jönsson, S. Majewski, M. Shetrone, J. Sobeck, G. Stringfellow, J. Teske, O. Zamora, O. Zamora, G. Zasowski, R. Carrera, K. Stassun, J. G. Fernández-Trincado, J. G. Fernández-Trincado, S. Villanova, D. Minniti, F. Santana   +27 more
semanticscholar   +1 more source

Machine learning in APOGEE: Identification of stellar populations through chemical abundances [PDF]

Astronomy & Astrophysics, 2019
Context. The vast volume of data generated by modern astronomical surveys offers test beds for the application of machine-learning. In these exploratory applications, it is important to evaluate potential existing tools and determine those that are ...
R. Garcia-Dias, C. Prieto, J. Almeida, P. Palicio   +3 more
semanticscholar   +1 more source