Results 21 to 30 of about 226,393 (319)

Neon and Sulfur Abundances of Planetary Nebulae in the Magellanic Clouds [PDF]

, 2007
The chemical abundances of neon and sulfur for 25 planetary nebulae (PNe) in the Magellanic Clouds are presented. These abundances have been derived using mainly infrared data from the Spitzer Space Telescope.
Aller L. H., de Graauw T., Feldman U., Fluks M. A., Grevesse N., J. Bernard‐Salas, J. R. Houck, Monk D. J., P. W. Morris, Pena M., S. Gutenkunst, S. R. Pottasch, Zijlstra A. A.   +12 more
core   +4 more sources

Constraining cosmic scatter in the Galactic halo through a differential analysis of metal-poor stars [PDF]

, 2017
© ESO 2017.Context. The chemical abundances of metal-poor halo stars are important to understanding key aspects of Galactic formation and evolution. Aims.
Amanda Karakas, Andrievsky, Andrievsky, Andrievsky, Andrievsky, Andrievsky, Aoki, Aoki, Arnone, Asplund, Asplund, Audouze, Baumueller, Baumueller, Bensby, Bergemann, Bergemann, Biazzo, Boesgaard, Bonifacio, Bonifacio, Busso, Busso, Carlos, Caughlan, Cayrel, Cescutti, Chiaki Kobayashi, Chiappini, Chieffi, Civitarese, Coc, Coc, Coc, Cohen, Cowan, Cyburt, Eggen, Ferraro, Ferraro, Fishlock, François, Frischknecht, Fu, Gustafsson, Hampel, Hannaford, Hansen, Hartog, Heger, Henrique Reggiani, Herwig, Hollek, Hou, Iocco, Jacobson, Ji, Jorge Meléndez, Karakas, Karakas, Keller, Kim, Kobayashi, Kobayashi, Kobayashi, Kohri, Lai, Lawler, Lind, Lind, Liu, Liu, Maeda, McCrea, McWilliam, Meléndez, Meléndez, Meléndez, Meléndez, Meyer, Meynet, Monroe, Nissen, Nissen, Nissen, Nomoto, Norris, Norris, O’Malley, Pignatari, Placco, Placco, Placco, Pllumbi, Ramírez, Ramírez, Ramírez, Ramírez, Ramírez, Ramírez, Reggiani, Richard, Roederer, Ryan, Ryan, Ryan, Salvati, Santucci, Scholz, Schuster, Searle, Shigeyama, Sills, Sitnova, Sneden, Spina, Spite, Spite, Spite, Suda, Suda, Thielemann, Tucci Maia, Tucci Maia, Umeda, Vinicius Placco, Wood, Yamada, Yi, Yong, Zhao, Önehag   +131 more
core   +3 more sources

High-resolution Chemical Abundances of the Nyx Stream

The Astrophysical Journal, 2023
Nyx is a nearby, prograde, and high-eccentricity stellar stream physically contained in the thick disk, but its origin is unknown. Nyx could be the remnant of a disrupted dwarf galaxy, in which case the associated dark matter substructure could affect ...
Shuyu Wang, Lina Necib, Alexander P. Ji, Xiaowei Ou, Mariangela Lisanti, Mithi A. C. de los Reyes, Allison L. Strom, Mimi Truong   +7 more
doaj   +1 more source

Chemical sensitivity to the ratio of the cosmic-ray ionization rates of He and H2 in dense clouds [PDF]

, 2006
Aim: To determine whether or not gas-phase chemical models with homogeneous and time-independent physical conditions explain the many observed molecular abundances in astrophysical sources, it is crucial to estimate the uncertainties in the calculated ...
Baldwin, Bergin, Boger, Charnley, Dalgarno, E. Herbst, F. Selsis, G. Massacrier, Glassgold, Graedel, Herbst, Le Bourlot, Le Bourlot, Le Teuff, Lee, Pagani, Pineau des Forets, Shalabiea, Smith, Snell, Terzieva, V. Wakelam, Wakelam, Wakelam, Wakelam   +24 more
core   +3 more sources

Chemical Abundances in Galactic Bulge Pn [PDF]

Symposium - International Astronomical Union, 1993
We present abundance determinations, in particular of carbon, and C/O ratios, for 11 Galactic bulge planetary nebulae (PN) based on our low resolution UV data from IUE observations and optical spectrophotometry from the Anglo-Australian Telescope. We compare the observed abundances with those predicted by dredge-up theory for the high metallicity ...
N. A. Walton, M. J. Barlow, R. E. S. Clegg   +2 more
openaire   +1 more source

Chemical Abundances in Symbiotic Stars [PDF]

The Astrophysical Journal, 2008
We have carried out a study of the chemical abundances of $^1$H, $^4$He, $^{12}$C, $^{13}$C, $^{14}$N, $^{15}$N, $^{16}$O, $^{17}$O, $^{20}$Ne and $^{22}$Ne in symbiotic stars (SSs) by means of a population synthesis code. We find that the ratios of the number of O-rich SSs to that of C-rich SSs in our simulations are between 3.4 and 24.1, depending on
Lu, Guoliang, Zhu, Chunhua, Han, Zhanwen, Wang, Zhaojun   +3 more
openaire   +2 more sources

Li-rich Giants Identified from LAMOST DR8 Low-resolution Survey

The Astronomical Journal, 2023
A small fraction of giants possess photospheric lithium (Li) abundance higher than the value predicted by the standard stellar evolution models, and the detailed mechanisms of Li enhancement are complicated and lack a definite conclusion.
Beichen Cai, Xiaoming Kong, Jianrong Shi, Qi Gao, Yude Bu, Zhenping Yi   +5 more
doaj   +1 more source

Chemical abundances in Seyfert galaxies VI. Empirical abundance calibration

, 2021
9 pages, 7 figures, accepted for publication in ...
Dors, L, O.
openaire   +2 more sources

Chemical Abundances as Population Tracers [PDF]

, 2013
Chapter to appear in textbook "Planets, Stars & Stellar Systems", Vol. 5, Ed. G. Gilmore, Springer-Verlag.
openaire   +4 more sources

Search for Extremely Metal-poor Stars with Gemini-N/Graces. I. Chemical-abundance Analysis

The Astrophysical Journal, 2023
We present stellar parameters and abundances of 13 elements for 18 very metal-poor (VMP; [Fe/H] < –2.0) stars, selected as extremely metal-poor (EMP; [Fe/H] < –3.0) candidates from the Sloan Digital Sky Survey and Large sky Area Multi-Object Fiber ...
Miji Jeong, Young Sun Lee, Timothy C. Beers, Vinicius M. Placco, Young Kwang Kim, Jae-Rim Koo, Ho-Gyu Lee, Soung-Chul Yang   +7 more
doaj   +1 more source