Observing early stellar nucleosynthesis

2021 ◽  
Author(s):  
Nils Ryde ◽  
Graham Harper
Keyword(s):  
Stellar Nucleosynthesis

scholarly journals STELLAR NUCLEOSYNTHESIS IN THE HYADES OPEN CLUSTER

2009 ◽  
Vol 701 (1) ◽  
pp. 837-849 ◽  
Author(s):  
Simon C. Schuler ◽  
Jeremy R. King ◽  
Lih-Sin The
Keyword(s):  
Open Cluster ◽  
Stellar Nucleosynthesis

Nucleosynthesis

1986 ◽  
Vol 320 (1556) ◽  
pp. 557-564 ◽  
Keyword(s):  
Light Element ◽  
Hubble Constant ◽  
Big Bang ◽  
Element Abundances ◽  
Stellar Nucleosynthesis ◽  
Baryonic Density ◽  
Redshift Surveys ◽  
A Value ◽  
First Case ◽  
The Universe

Both Big-Bang and stellar nucleosynthesis have outcomes related to the density of baryonic matter, but whereas in the first case there is a standard model that makes very precise predictions of light element abundances as a function of the mean density of baryons in the Universe, in the second case various uncertainties permit only very limited conclusions to be drawn. As far as Big-Bang synthesis and the light elements are concerned, existing results on D, 3 He and 7 Li indicate a value of Ω N h 2 0 greater than 0.01 and less than 0.025, where Ω N is the ratio of baryonic density to the closure density and h 0 is the Hubble constant in units of 100 km s -1 Mpc -1 ; probably 0.5 < h 0 < 1. New results on the primordial helium abundance give a still tighter upper limit to Ω N ,Ω N h 2 0 < 0.013, which when compared with redshift surveys giving Ω > 0.05 implies that the observed matter can all be baryonic only if the various uncertainties are stretched to their limits.

scholarly journals Observing the Nucleosynthesis from Core Collapse Supernovae

1988 ◽  
Vol 108 ◽  
pp. 383-393
Author(s):  
Claes Fransson
Keyword(s):  
Supernova Remnants ◽  
Direct Evidence ◽  
Optical Observations ◽  
Core Collapse ◽  
Valuable Insight ◽  
Sources Of Information ◽  
X Ray ◽  
Stellar Nucleosynthesis ◽  
Plasma Effects ◽  
Indirect Sources

Since the appearance of the classical papers on stellar nucleosynthesis in the 1950’s most of the observational tests have been through indirect sources of information. Even though this has been rather successful (cf. various contributions in this volume), it represents only an average over all sources, yielding little information about specific stars. The most direct evidence comes from observations of young galactic supernova remnants (age less than ∼103 years). Unfortunately, the analysis of X-ray data are hampered by a lack of understanding of the detailed physics, eg. non-equilibrium and plasma effects, as well as by observational problems (Itoh and Nomoto, 1987). Optical observations (cf. Raymond, 1984) have given some valuable insight of eg. the oxygen-rich remnants. The analysis of these are, however, suffering from the fact that only a small fraction of the mass is seen in the optical.

scholarly journals Chlorine-bearing molecules in molecular absorbers at intermediate redshifts

2019 ◽  
Vol 629 ◽  
pp. A128 ◽  
Author(s):  
S. H. J. Wallström ◽  
S. Muller ◽  
E. Roueff ◽  
R. Le Gal ◽  
J. H. Black ◽  
...  
Keyword(s):  
Molecular Hydrogen ◽  
Chemical Properties ◽  
Abundance Ratio ◽  
The Other ◽  
Trace Gas ◽  
Line Of Sight ◽  
Isotopic Ratios ◽  
Stellar Nucleosynthesis ◽  
Chemical Models ◽  
Intermediate Redshifts

We use observations of chlorine-bearing species in molecular absorbers at intermediate redshifts to investigate chemical properties and 35Cl/37Cl isotopic ratios in the absorbing sightlines. Chloronium (H2Cl+) is detected along three independent lines of sight in the z = 0.89 and z = 0.68 molecular absorbers located in front of the lensed quasars PKS 1830−211 and B 0218+357, respectively. Hydrogen chloride (HCl) was observed only toward PKS 1830−211, and is found to behave differently from H2Cl+. It is detected in one line of sight with an abundance ratio [H2Cl+] / [HCl] ∼1, but remains undetected in the other, more diffuse, line of sight, with a ratio [H2Cl+] / [HCl] > 17. The absorption profiles of these two chlorine-bearing species are compared to other species and discussed in terms of the physical properties of the absorbing gas. Our findings are consistent with the picture emerging from chemical models where different species trace gas with different molecular hydrogen fraction. The 35Cl/37Cl isotopic ratios are measured in the different lines of sight and are discussed in terms of stellar nucleosynthesis.

scholarly journals OCCASO – III. Iron peak and α elements of 18 open clusters. Comparison with chemical evolution models and field stars

2019 ◽  
Vol 490 (2) ◽  
pp. 1821-1842 ◽  
Author(s):  
L Casamiquela ◽  
S Blanco-Cuaresma ◽  
R Carrera ◽  
L Balaguer-Núñez ◽  
C Jordi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Nucleosynthesis ◽  
Solar Abundances ◽  
Red Giant

ABSTRACT The study of open-cluster chemical abundances provides insights on stellar nucleosynthesis processes and on Galactic chemo-dynamical evolution. In this paper we present an extended abundance analysis of 10 species (Fe, Ni, Cr, V, Sc, Si, Ca, Ti, Mg, O) for red giant stars in 18 OCCASO clusters. This represents a homogeneous sample regarding the instrument features, method, line list and solar abundances from confirmed member stars. We perform an extensive comparison with previous results in the literature, and in particular with the Gaia FGK Benchmark stars Arcturus and $\mu$-Leo. We investigate the dependence of [X/Fe] with metallicity, Galactocentric radius (6.5 kpc &lt; RGC &lt; 11 kpc), age (0.3 Gyr &lt; Age &lt; 10 Gyr), and height above the plane (|z| &lt; 1000 pc). We discuss the observational results in the chemo-dynamical framework, and the radial migration impact when comparing with chemical evolution models. We also use APOGEE DR14 data to investigate the differences between the abundance trends in RGC and |z| obtained for clusters and for field stars.

scholarly journals Heavy element evolution in the inner regions of the Milky Way

2020 ◽  
Vol 494 (4) ◽  
pp. 5534-5541 ◽  
Author(s):  
F Matteucci ◽  
A Vasini ◽  
V Grisoni ◽  
M Schultheis
Keyword(s):  
Heavy Element ◽  
Milky Way ◽  
Current Knowledge ◽  
Experiment Data ◽  
Stellar Nucleosynthesis ◽  
Abundance Patterns ◽  
Evolution Experiment ◽  
Element Evolution ◽  
Chemical Evolution Model ◽  
Detailed Chemical

ABSTRACT We present results for the evolution of the abundances of heavy elements (O, Mg, Al, Si, K, Ca, Cr, Mn, Ni, and Fe) in the inner Galactic regions (RGC ≤ 4 kpc). We adopt a detailed chemical evolution model already tested for the Galactic bulge and compare the results with Apache Point Observatory Galactic Evolution Experiment data. We start with a set of yields from the literature that are considered the best to reproduce the abundance patterns in the solar vicinity. We find that, in general, the predicted trends nicely reproduce the data but in some cases either the trend or the absolute values of the predicted abundances need to be corrected, even by large factors, in order to reach the best agreement. We suggest how the current stellar yields should be modified to reproduce the data and we discuss whether such corrections are reasonable in the light of the current knowledge of stellar nucleosynthesis. However, we also critically discuss the observations. Our results suggest that Si, Ca, Cr, and Ni are the elements for which the required corrections are the smallest, while for Mg and Al moderate modifications are necessary. On the other hand, O and K need the largest corrections to reproduce the observed patterns, a conclusion already reached for solar vicinity abundance patterns, with the exception of oxygen. For Mn, we apply corrections already suggested in previous works.

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