Results 61 to 70 of about 50,982 (241)

Evolution of Li, Be and B in the Galaxy [PDF]

, 2001
In this paper we study the production of Li, Be and B nuclei by Galactic cosmic ray spallation processes. We include three kinds of processes: (i) spallation by light cosmic rays impinging on interstellar CNO nuclei (direct processes); (ii) spallation by
Bonifacio P., Chmielewski Y., Daniele Galli, Dodds D., Federico Ferrini, Giada Valle, Goldstein M. L., Hanon P., Ip W. H., Lemoine M., Meneguzzi M., Meyer J.-P., Mitler H. E., Primas F., Primas F., Primas F., Sandage A., Shore S. N., Steven N. Shore, Tinsley B. M., Vangioni-Flam E.   +20 more
core   +2 more sources

Helium Abundance at the Galactic Center

The Astrophysical Journal, 1974
We suggest that the low abundance of ionized helium in H II regions at the galactic center can be explained by selective absorption of helium-ionizing photons by dust within the ionized gas. This model requires an extrapolation to 500 A of the rapid increase of the extinction measured between 1500 A and 1000 A with the Copernicus satellite, and it ...
E. L. Wright, M. Jura
openaire   +2 more sources

Abundances of Chemical Elements in Open Star Clusters as Indicators of their Nature

Open Astronomy, 2015
Applying a compilled catalog, we find that the relative abundances of α-elements in open clusters and in field stars of the thin disk of the Galaxy show different dependencies on metallicity, age and parameters of their Galactic orbits.
Marsakov V. A., Gozha M. L., Koval’ V. V., Shpigel’ L. V.   +3 more
doaj   +1 more source

Constraining planet structure and composition from stellar chemistry: trends in different stellar populations [PDF]

, 2017
The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems.
Adibekyan, V., Barros, S. C. C., Delgado-Mena, E., Demangeon, O., Dorn, C., Faria, J., Israelian, G., Mordasini, C., Noack, L., Santos, N. C., Sousa, S. G.   +10 more
core   +2 more sources

Abundances and Evolution of Lithium in the Galactic Halo and Disk [PDF]

The Astrophysical Journal, 2001
We have measured the Li abundance of 18 stars with -2 -0.5. We speculate that cool-bottom processing (production) of Li in low-mass stars may provide an important late-appearing source of Li, without attendant Fe production, that might explain the Li production in the young disk.
Timothy C. Beers, Francesca Matteucci, Francesca Matteucci, Toshitaka Kajino, Sean G. Ryan, Katarina Rosolankova, Takeru K. Suzuki, Donatella Romano   +7 more
openaire   +4 more sources

He-rich Hot Subdwarf Stars Observed in Gaia DR3 and LAMOST DR7: Carbon and Nitrogen Abundances and Kinematics

The Astrophysical Journal Supplement Series
We conducted an analysis of the abundances of He, C, and N in 210 He-rich hot subdwarfs observed within both the Gaia Data Release 3 (DR3) and LAMOST DR7 data sets.
Yangping Luo, Péter Németh, Kun Wang, Yang Pan   +3 more
doaj   +1 more source

MOLYBDENUM AND RUTHENIUM ABUNDANCES IN COOL STARS OF THE GALACTIC DISC

Odessa Astronomical Publications, 2017
We  revise  the  molybdenum  and  ruthenium abundances in  FGK stars with metallicities  ranging from −1.0 < [Fe/H] < +0.3. The observed stars belong to the  substructures  of  the  Galaxy.  The  observations  were conducted using the 1.93 m telescope at
T. I. Gorbaneva, T. V. Mishenina
doaj   +1 more source

Determination of Abundances of Chemical Elements in Open Star Clusters of the Galaxy

Open Astronomy, 2016
Spectroscopic determinations of the relative abundances of chemical elements produced in different nuclear-synthesis processes, [el/Fe], are collected for 90 open star clusters of the Galaxy using data from 109 papers published between 1991 and 2015 ...
Gozha M. L., Koval’ V. V., Marsakov V. A.   +2 more
doaj   +1 more source

Mn abundances in the stars of the Galactic disc with metallicities -1.0 < [Fe/H] < 0.3 [PDF]

, 2015
In this work we present and discuss the observations of the Mn abundances for 247 FGK dwarfs, located in the Galactic disc with metallicity -1 < [Fe/H]< +0.3.
Gorbaneva, Tatyana Ivanovna, Korotin, Sergey, Mishenina, Tamara, Pignatari, M., Thielemann, Friedrich-Karl   +4 more
core   +2 more sources

On the Abundance Gradient of the Galactic Disk

, 2000
6 pages, 2 ...
Martins, Lucimara P., Viegas, Sueli M. M.   +1 more
openaire   +2 more sources