Results 51 to 60 of about 226,407 (198)

The building up of the disk galaxy M33 and the evolution of the metallicity gradient

, 2007
The evolution of radial gradients of metallicity in disk galaxies and its relation with the disk formation are not well understood. Theoretical models of galactic chemical evolution make contrasting predictions about the time evolution of metallicity ...
Aller, Arnett, Aubert, Beaulieu, Block, Block, Brooks, Bullock, Chabrier, Chang, Chiappini, Chiappini, Chiappini, Chieffi, Ciardullo, Ciardullo, Corbelli, Corbelli, Crockett, D. Galli, Davidge, de Boer, Devereux, Diaz, E. Corbelli, Elmegreen, Engargiola, Ferrini, Ferrini, Ferrini, Ferrini, Freedman, Freeman, Friel, Gallagher, Galletti, Garnett, Gavilán, Goetz, Henry, Henry, Henry, Herrero, Herwig, Heyer, Hippelein, Hirschi, Holmberg, Hoopes, Hou, Israel, Kennicutt, Kennicutt, Kennicutt, Keres, Kim, Koeppen, Kroupa, Kroupa, Kwitter, L. Magrini, Maciel, Maciel, Maciel, Maciel, Magrini, Magrini, Magrini, Marigo, McCarthy, McConnachie, Mollà, Mollà, Mollà, Monteverde, Monteverde, Naab, Newton, Portinari, Portinari, Regan, Richer, Romano, Rowe, Salpeter, Sandage, Scalo, Scalo, Smith, Stanghellini, Stephens, Talbot, Thielemann, Tiede, Tinsley, Tosi, Urbaneja, Venn, Vílchez, Wakker, Westmeier, Willner, Woosley, Wyse, Young   +104 more
core   +1 more source

Chemical Abundances of the S star GZ Peg [PDF]

, 2009
The chemical compositions of stars from the Asymptotic Giant Branch are still poorly known due to the low temperatures of their atmospheres and therefore the presence of many molecular transitions hampering the analysis of atomic lines.
Allen, Alonso, Goriely, Gustafsson, Jorissen, L. Pompéia, Lebzelter, Smiljanic, Woolf   +8 more
core   +1 more source

Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams

The Astrophysical Journal
We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra. Abundances for 27 elements, ranging
K. B. Webber, T. T. Hansen, J. L. Marshall, Alexander P. Ji, Ting S. Li, Gary S. Da Costa, Lara R. Cullinane, Denis Erkal, Sergey E. Koposov, Kyler Kuehn, Geraint F. Lewis, Dougal Mackey, Sarah L. Martell, Andrew B. Pace, Nora Shipp, Jeffrey D. Simpson, Zhen Wan, Daniel B. Zucker, Victor A. Alvarado, Joss Bland-Hawthorn, Guilherme Limberg, Gustavo E. Medina, Sam A. Usman   +22 more
doaj   +1 more source

The ¹⁷O/¹⁸O Ratio of Post-AGB Sources: Canonical and Non-Canonical Populations

Galaxies
Stellar evolution models serve as tools to derive stellar parameters from elemental and isotopic abundance ratios. For low-to-intermediate mass evolved stars, C/O, 12C/13C, and 17O/18O ratios are proxies of the initial mass, a largely unknown parameter ...
Javier Alcolea, Elisa Masa, Theo Khouri, Miguel Santander-García, Iván Gallardo Cava, Hans Olofsson, Carmen Sánchez Contreras, Valentín Bujarrabal, Wouter H. T. Vlemmings, Daniel Tafoya   +9 more
doaj   +1 more source

On the Influence of Uncertainties in Chemical Reaction Rates on Results of the Astrochemical Modelling

, 2003
With the chemical reaction rate database UMIST95 (Millar et al. 1997) we analyze how uncertainties in rate constants of gas-phase chemical reactions influence the modelling of molecular abundances in the interstellar medium.
A. I. Vasyunin, A. M. Sobolev, B. E. Turner, D. A. Semenov, D. P. Ruffle, D. S. Wiebe, E. Dishoeck van, G. Pineau Forêts des, H.-H. Lee, M. Matsumoto, R. Terzieva, S. W. Stahler, T. J. Millar, Y. H. Teuff Le, Y. Hirahara, Yu. Aikawa, Z.-Y. Li   +16 more
core   +1 more source

CHEMICAL ABUNDANCES IN CLUSTERS OF GALAXIES

, 1995
25 pages of uuencoded compressed PostScript. 4 PostScript figures and 4 PostScript tables available from http://www-astro.physics.ox.ac.uk/~bkg/gibson.html Accepted for publication in Astronomy & Astrophysics.
MATTEUCCI, MARIA FRANCESCA, Gibson, B. K.   +1 more
openaire   +3 more sources

A Systematic NLTE Study of Very Metal-poor Stars with Metallicity down to −4.3 dex. VI. Light Neutron-capture Elements and the Sr–Na Correlation as a Signature of Spinstar Nucleosynthesis in the Early Galaxy

The Astrophysical Journal
We present a non–local thermodynamic equilibrium (NLTE) abundance analysis of the light neutron-capture elements Sr, Y, and Zr in a sample of 103 very metal-poor stars spanning −4.3 ≲ [Fe/H] ≲ −1.7, based on high-resolution Subaru/HDS spectra and ...
Sofya Alexeeva, Hongliang Yan, Gang Zhao, Jianrong Shi, Haining Li, Shuai Liu, Zeming Zhou, Junbo Zhang, Jingkun Zhao, Yaqian Wu, Yuqin Chen, Huiling Chen, Huawei Zhang, Wako Aoki   +13 more
doaj   +1 more source

Optical Spectroscopy and Photoionization Model of Planetary Nebula NGC 6572

Journal of Mathematical and Fundamental Sciences
We investigated NGC 6572 through optical spectroscopy to determine its kinematical and chemical properties. Two intermediate dispersion spectra (R~5000) centered around Hα and Hβ were used to derive the nebular expansion velocity from emission lines ...
Muhammad Fajrin, Hakim Luthfi Malasan, Evan Irawan Akbar   +2 more
doaj   +1 more source

Chemical composition of clump stars in the open cluster NGC 6134

, 2010
We present an analysis of high-resolution spectra of six core-helium-burning "clump" stars in the open cluster NGC 6134. Atmospheric parameters T_eff, log_g, v_t, and [Fe/H] were determined in our previous study by Carretta et al. (2004).
Bragaglia, Angela, Carretta, Eugenio, Gratton, Raffaele, Mikolaitis, Šarūnas, Tautvaišienė, Gražina   +4 more
core   +1 more source

Chemical abundances of solar neighbourhood RR Lyrae stars★ [PDF]

Monthly Notices of the Royal Astronomical Society, 2015
We have analysed a sample of 18 RR Lyrae stars (17 fundamental-mode - RRab - and one first overtone - RRc) and three Population II Cepheids (two BL Her stars and one W Vir star), for which high-resolution (R $\ge$30000), high signal-to-noise (S/N$\ge$30) spectra were obtained with either SARG at the Telescopio Nazionale Galileo (La Palma, Spain) or ...
Pancino, E., Britavskiy, N., Romano, D., Cacciari, C., MUCCIARELLI, ALESSIO, Clementini, G.   +5 more
openaire   +3 more sources