Carbon Isotopic Chemistry

AbstractA major avenue in the study of the Galaxy is the investigation of stellar populations and Galactic chemical evolution by stellar spectroscopy. Due to the dust obscuration, stars in the centre of the Galaxy can only be observed in the near-IR wavelength region. However, existing line lists in this wavelength region are demonstratively not of good enough quality for use in stellar spectroscopy. In response to this, we have developed an empirical astrophysical line list in the K-band based on modelling against the Sun and testing against Arcturus. Of ca. 700 identified interesting lines about 570 lines have been assigned empirically determined values.

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Impact of Hypernova νp-process Nucleosynthesis on the Galactic Chemical Evolution of Mo and Ru

The Astrophysical Journal ◽

10.3847/1538-4357/ac34f8 ◽

2022 ◽

Vol 924 (1) ◽

pp. 29

Author(s):

Hirokazu Sasaki ◽

Yuta Yamazaki ◽

Toshitaka Kajino ◽

Motohiko Kusakabe ◽

Takehito Hayakawa ◽

...

Keyword(s):

Theoretical Prediction ◽

Observational Data ◽

Chemical Evolution ◽

Elemental Abundance ◽

Core Collapse ◽

Galactic Chemical Evolution ◽

Main Contributor ◽

Elemental Abundances ◽

The Galaxy ◽

Low Metallicity

Abstract We calculate the Galactic Chemical Evolution of Mo and Ru by taking into account the contribution from ν p-process nucleosynthesis. We estimate yields of p-nuclei such as 92,94Mo and 96,98Ru through the ν p-process in various supernova progenitors based upon recent models. In particular, the ν p-process in energetic hypernovae produces a large amount of p-nuclei compared to the yield in ordinary core-collapse SNe. Because of this, the abundances of 92,94Mo and 96,98Ru in the Galaxy are significantly enhanced at [Fe/H] = 0 by the ν p-process. We find that the ν p-process in hypernovae is the main contributor to the elemental abundance of 92Mo at low metallicity [Fe/H] < −2. Our theoretical prediction of the elemental abundances in metal-poor stars becomes more consistent with observational data when the ν p-process in hypernovae is taken into account.

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The chemical evolution of the Galaxy

Symposium - International Astronomical Union ◽

10.1017/s0074180900243210 ◽

1985 ◽

Vol 106 ◽

pp. 587-596

Author(s):

Bruce A. Twarog

Keyword(s):

Star Formation ◽

Galaxy Evolution ◽

Chemical Evolution ◽

Gas Dynamics ◽

Common Point ◽

Galactic Chemical Evolution ◽

Stellar Nucleosynthesis ◽

Double Edge ◽

The Galaxy ◽

Double Edge Sword

Over the last few years, our picture of the chemical evolution of the Galaxy has changed substantially. These changes are of interest because chemical evolution provides a common point of contact for most astrophysical processes of importance to galaxy evolution. By astrophysical processes we mean star formation, stellar nucleosynthesis, gas dynamics, etc. An understanding of galactic chemical evolution would allow us to place constraints on all of these topics simultaneously. This property, however, is a double-edge sword because, with so many variables involved, unique solutions to problems in chemical evolution are almost impossible.

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Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310001213 ◽

2009 ◽

Vol 5 (S265) ◽

pp. 438-439

Author(s):

Eduardo M. Penteado ◽

Helio J. Rocha-Pinto

Keyword(s):

Gas Phase ◽

Chemical Evolution ◽

Chemical Compositions ◽

Small Bodies ◽

Interstellar Clouds ◽

Elemental Abundances ◽

Habitable Zones ◽

Consistent Model ◽

The Galaxy ◽

Rocky Planets

AbstractInterstellar clouds are the sites where many molecules believed important for the early life are produced. The collapse of such clouds may give birth to stars hosting planetary systems. During the formation of such systems, molecules formed in the molecular cloud, aggregated into grains, can be incorporated in protoplanets, influencing the chemical evolution of the environment, probably affecting the chances for appearance of life on rocky planets located at the stellar habitable zones. Moreover, small bodies, like comets, can carry some of these molecules to inner planets of their systems. Using astrochemical equations, we describe the evolution of the abundance of such molecules at the gas phase from several initial interstellar compositions. These varying initial chemical compositions consider the change of the elemental abundances predicted by a self-consistent model of the chemical evolution of the Galaxy. A system of first order differential equations that describes the abundances of each molecule is solved numerically. This poster describes an innovative attempt to link the astrochemistry equations with the Galactic chemical evolution.

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Heavy Element Nucleosynthesis

EPJ Web of Conferences ◽

10.1051/epjconf/201818401007 ◽

2018 ◽

Vol 184 ◽

pp. 01007

Author(s):

Mounib F. El Eid

Keyword(s):

Chemical Evolution ◽

Neutron Capture ◽

Heavy Element ◽

Slow Neutron ◽

Heavy Elements ◽

Galactic Chemical Evolution ◽

Physical Processes ◽

The Galaxy ◽

R Process

This contribution deals with the important subject of the nucleosynthesis of heavy elements in the Galaxy. After an overview of several observational features, the physical processes responsible mainly for the formation of heavy elements will be described and linked to possible stellar sites and to galactic chemical evolution. In particular, we focus on the neutron-capture processes, namely the s-process (slow neutron capture) and the r-process (rapid neutron capture) and discuss some problems in connection with their sites and their outcome. The aim is to give a brief overview on the exciting subject of the heavy element nucleosynthesis in the Galaxy, emphasizing its importance to trace the galactic chemical evolution and illustrating the challenge of this subject.

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He and Ne Ages of Large Presolar Silicon Carbide Grains: Solving the Recoil Problem

Publications of the Astronomical Society of Australia ◽

10.1071/as08039 ◽

2009 ◽

Vol 26 (3) ◽

pp. 297-302 ◽

Cited By ~ 10

Author(s):

Ulrich Ott ◽

Philipp R. Heck ◽

Frank Gyngard ◽

Rainer Wieler ◽

Frédéric Wrobel ◽

...

Keyword(s):

Silicon Carbide ◽

Cosmic Rays ◽

Chemical Evolution ◽

Cosmic Ray ◽

Galactic Chemical Evolution ◽

Correction Procedure ◽

Presolar Grains ◽

The Past ◽

Grain Formation ◽

The Galaxy

AbstractKnowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of μm) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC ‘Jumbo’ grains that range from close to zero to ∼850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic rays.

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Galactic evolution of D, 3He and 4He

Proceedings of the International Astronomical Union ◽

10.1017/s174392131000459x ◽

2009 ◽

Vol 5 (S268) ◽

pp. 431-440

Author(s):

Donatella Romano

Keyword(s):

Magnetic Fields ◽

Chemical Evolution ◽

Globular Clusters ◽

Milky Way ◽

Galactic Evolution ◽

Galactic Chemical Evolution ◽

Low Mass Stars ◽

Local Abundance ◽

The Galaxy ◽

Low Mass

AbstractThe uncertainties which still plague our understanding of the evolution of the light nuclides D, 3He and 4He in the Galaxy are described. Measurements of the local abundance of deuterium range over a factor of 3. The observed dispersion can be reconciled with the predictions on deuterium evolution from standard Galactic chemical evolution models, if the true local abundance of deuterium proves to be high, but not too high, and lower observed values are due to depletion onto dust grains. The nearly constancy of the 3He abundance with both time and position within the Galaxy implies a negligible production of this element in stars, at variance with predictions from standard stellar models which, however, do agree with the (few) measurements of 3He in planetary nebulae. Thermohaline mixing, inhibited by magnetic fields in a small fraction of low-mass stars, could in principle explain the complexity of the overall scenario. However, complete grids of stellar yields taking this mechanism into account are not available for use in chemical evolution models yet. Much effort has been devoted to unravel the origin of the extreme helium-rich stars which seem to inhabit the most massive Galactic globular clusters. Yet, the issue of 4He evolution is far from being fully settled even in the disc of the Milky Way.

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Evolution of D and 3He in the Galaxy

Symposium - International Astronomical Union ◽

10.1017/s0074180900167270 ◽

2000 ◽

Vol 198 ◽

pp. 525-534 ◽

Cited By ~ 3

Author(s):

Monica Tosi

Keyword(s):

Big Bang ◽

Isotopic Ratios ◽

Galactic Chemical Evolution ◽

Low Mass Stars ◽

Carbon Isotopic ◽

The Galaxy ◽

Low Mass ◽

Red Giant ◽

The Big Bang ◽

Self Consistency

The predictions of Galactic chemical evolution models for D and 3He are described in connection with those on the other Galactic quantities for which observational constraints are available.Models in agreement with the largest set of data predict deuterium depletions from the Big Bang to the present epoch smaller than a factor of 3 and do not allow for D/H primordial abundances larger than ∼ 4 × 10—5. Models predicting higher D consumption do not reproduce other observed features of our Galaxy.If both the primordial D and 3He are low, models assuming that 90% of low-mass stars experience an extra-mixing during the red giant phase reproduce all the 3He observed abundances. The same percentage allows to fit also the observed carbon isotopic ratios, thus supporting the self-consistency of the extra-mixing mechanism.

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Galactic Chemical Evolution of the s Process from AGB Stars

Publications of the Astronomical Society of Australia ◽

10.1071/as08053 ◽

2009 ◽

Vol 26 (3) ◽

pp. 153-160 ◽

Cited By ~ 25

Author(s):

Alessandra Serminato ◽

Roberto Gallino ◽

Claudia Travaglio ◽

Sara Bisterzo ◽

Oscar Straniero

Keyword(s):

Solar System ◽

Chemical Evolution ◽

Asymptotic Giant Branch ◽

Heavy Elements ◽

Agb Stars ◽

Galactic Chemical Evolution ◽

Element Analysis ◽

Residual Method ◽

The Galaxy ◽

Process Element

AbstractWe follow the chemical evolution of the Galaxy for the s elements using a Galactic chemical evolution (GCE) model, as already discussed by Travaglio et al. (1999, 2001, 2004), with a full updated network and refined asymptotic giant branch (AGB) models. Calculations of the s contribution to each isotope at the epoch of the formation of the solar system is determined by following the GCE contribution by AGB stars only. Then, using the r-process residual method we determine for each isotope their solar system r-process fraction, and recalculate the GCE contribution of heavy elements accounting for both the s and r process. We compare our results with spectroscopic abundances at various metallicities of [Sr,Y,Zr/Fe], of [Ba,La/Fe], of [Pb/Fe], typical of the three s-process peaks, as well as of [Eu/Fe], which in turn is a typical r-process element. Analysis of the various uncertainties involved in these calculations are discussed.

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