A minimum dilution scenario for supernovae and consequences for extremely metal-poor stars

ABSTRACT To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in the first stars and their supernova (SN). In this approach, modelled SN yields are compared to the observed abundance patterns in extremely metal-poor stars. The method typically only uses the abundance ratios, i.e. the yields are diluted to the observed level. Following the usual assumption of spherical symmetry we compute a simple lower limit of the mass an SN can mix with and find that it is consistent with all published simulations of early chemical enrichment in the interstellar medium. For three different cases, we demonstrate that this dilution limit can change the conclusions from the abundance fitting. There is a large discrepancy between the dilution found in simulations of SN explosions in minihaloes and the dilution assumed in many abundance fits. Limiting the dilution can significantly alter the likelihood of which supernovae are possible progenitors of observed CEMP-no stars. In particular, some of the faint, very low yield SNe, which have been suggested as models for the abundance pattern of SMSS0313−6708, cannot explain the measured metal abundances, as their predicted metal yields are too small by two orders of magnitude. Altogether, the new dilution model presented here emphasizes the need to better understand the mixing and dilution behaviour of aspherical SNe.

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Core Collapse Supernova Models and Nucleosynthesis

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313009198 ◽

2013 ◽

Vol 9 (S296) ◽

pp. 27-36

Author(s):

Ken'ichi Nomoto

Keyword(s):

Big Bang ◽

Elemental Abundance ◽

Core Collapse ◽

Solar Abundance ◽

First Stars ◽

Abundance Pattern ◽

Core Collapse Supernova ◽

Abundance Patterns ◽

Supernova Explosions ◽

The Big Bang

AbstractAfter the Big Bang, production of heavy elements in the early Universe takes place in the first stars and their supernova explosions. The nature of the first supernovae, however, has not been well understood. The signature of nucleosynthesis yields of the first supernovae can be seen in the elemental abundance patterns observed in extremely metal-poor stars. Interestingly, those abundance patterns show some peculiarities relative to the solar abundance pattern, which should provide important clues to understanding the nature of early generations of supernovae. We review the recent results of the nucleosynthesis yields of massive stars. We examine how those yields are affected by some hydrodynamical effects during the supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars.

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Nitrogen evolution in the halo, thick disc, thin disc, and bulge of the Galaxy

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2579 ◽

2021 ◽

Vol 508 (1) ◽

pp. 719-727

Author(s):

V Grisoni ◽

F Matteucci ◽

D Romano

Keyword(s):

Galactic Halo ◽

Massive Stars ◽

Chemical Elements ◽

Distribution Functions ◽

Abundance Pattern ◽

Origin And Evolution ◽

Thick Disc ◽

Thin Disc ◽

Abundance Patterns ◽

The Galaxy

ABSTRACT We study the evolution of nitrogen (N) in the Galactic halo, thick disc, thin disc, and bulge by comparing detailed chemical evolution models with recent observations. The models used in this work have already been constrained to explain the abundance patterns of α-elements and the metallicity distribution functions of halo, disc, and bulge stars; here, we adopt them to investigate the origin and evolution of N in the different Galactic components. First, we consider different sets of yields and study the importance of the various channels proposed for N production. Secondly, we apply the reference models to study the evolution of both the Galactic discs and bulge. We conclude that: i) primary N produced by rotating massive stars is required to reproduce the plateau in log(N/O) and [N/Fe] ratios at low metallicity, as well as the secondary and primary production from low- and intermediate-mass stars to reproduce the data of the thin disc; ii) the parallel model can provide a good explanation of the evolution of N abundance in the thick and thin discs, and we confirm that the thick disc has evolved much faster than the thin disc, in agreement with the results from the abundance patterns of other chemical elements; and iii) finally, we present new model predictions for N evolution in the Galactic bulge, and we show that the observations in bulge stars can be explained if massive stars rotate fast during the earliest phases of Galactic evolution, in agreement with findings from the abundance pattern of carbon.

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Chemical Abundances and Hierarchical Clustering

Symposium - International Astronomical Union ◽

10.1017/s0074180900197682 ◽

2004 ◽

Vol 217 ◽

pp. 264-265

Author(s):

P. B. Tissera ◽

D.G. Lambas

Keyword(s):

Interstellar Medium ◽

Hierarchical Clustering ◽

Stellar Population ◽

Intergalactic Medium ◽

Chemical Elements ◽

Building Blocks ◽

Chemical Abundances ◽

Energy Feedback ◽

Chemical Enrichment ◽

Central Regions

In this contribution we study the chemical enrichment of the interstellar medium and stellar population of the building blocks of current typical galaxies in the field, in cosmological hydrodynamics simulations. The simulations include detailed modeling of chemical enrichment by SNIa and SNII In our simulations the missing metal problem is caused by chemical elements being locked up in stars, in the central regions (or bulges) mainly. Supernova energy feedback could help to reduce this concentration by expelling metals to the intergalactic medium.

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Supernova Yields for Chemical Evolution Modeling

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313006327 ◽

2013 ◽

Vol 9 (S298) ◽

pp. 154-166

Author(s):

Ken'ichi Nomoto ◽

Tomoharu Suzuki

Keyword(s):

Chemical Evolution ◽

Massive Stars ◽

Elemental Abundance ◽

Solar Abundance ◽

Abundance Pattern ◽

Chemical Enrichment ◽

Abundance Patterns ◽

Yield Table ◽

Supernova Explosions ◽

Evolution Modeling

AbstractWe review the recent results of the nucleosynthesis yields of massive stars. We examine how those yields are affected by some hydrodynamical effects during the supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars. The elemental abundance patterns observed in extremely metal-poor stars show some peculiarities relative to the solar abundance pattern, which suggests the important contributions of hypernovae and faint supernovae in the early chemical enrichment of galaxies. These constraints on supernova nucleosynthesis are taken into account in the latest yield table for chemical evolution modeling.

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Suzaku observation of the metallicity in the interstellar medium of NGC 1316

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310009294 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 286-286

Author(s):

S. Konami ◽

K. Matsushita ◽

K. Sato ◽

R. Nagino ◽

N. Isobe ◽

...

Keyword(s):

Interstellar Medium ◽

Mass Loss ◽

Elliptical Galaxies ◽

Stellar Mass ◽

Metal Enrichment ◽

Abundance Pattern ◽

Type Ia ◽

History Of ◽

Metal Abundances ◽

Formation And Evolution

Metal abundances of the hot X-ray emitting interstellar medium (ISM) include important information to understand the history of star formation and evolution of galaxies. The metals are mainly synthesized by Type Ia (SNe Ia) and stellar mass loss in elliptical galaxies. The productions of stellar mass loss reflect stellar metallicity. SNe Ia mainly product Fe. Therefore, the abundance pattern of ISM can play key role to investigate the metal enrichment history.

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First Stars – Type Ib Supernovae Connection

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308024794 ◽

2008 ◽

Vol 4 (S255) ◽

pp. 182-188

Author(s):

Ken'ichi Nomoto ◽

Masaomi Tanaka ◽

Yasuomi Kamiya ◽

Nozomu Tominaga ◽

Keiichi Maeda

Keyword(s):

Kinetic Energy ◽

Main Sequence ◽

Gamma Ray ◽

Gamma Ray Bursts ◽

Core Collapse ◽

First Stars ◽

X Ray ◽

Chemical Enrichment ◽

Abundance Patterns ◽

Normal Core

AbstractThe very peculiar abundance patterns observed in extremely metal-poor (EMP) stars can not be explained by conventional normal supernova nucleosynthesis but can be well-reproduced by nucleosynthesis in hyper-energetic and hyper-aspherical explosions, i.e., Hypernovae (HNe). Previously, such HNe have been observed only as Type Ic supernovae. Here, we examine the properties of recent Type Ib supernovae (SNe Ib). In particular, SN Ib 2008D associated with the luminous X-ray transient 080109 is found to be a more energetic explosion than normal core-collapse supernovae. We estimate that the progenitor's main sequence mass is MMS = 20 − 25M⊙ with an explosion of kinetic energy of EK ~ 6.0 × 1051 erg. These properties are intermediate between those of normal SNe and hypernovae associated with gamma-ray bursts. Therefore, such energetic SNe Ib could also make an important contribution to the chemical enrichment in the early Universe.

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Explosive nucleosynthesis of a metal-deficient star as the source of a distinct odd-even effect in the solar twin HIP 11915

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slab010 ◽

2021 ◽

Vol 502 (1) ◽

pp. L104-L109

Author(s):

Jhon Yana Galarza ◽

Jorge Meléndez ◽

Amanda I Karakas ◽

Martin Asplund ◽

Diego Lorenzo-Oliveira

Keyword(s):

Signal To Noise Ratio ◽

Resolving Power ◽

Core Collapse ◽

The Sun ◽

Chemical Abundance ◽

Abundance Pattern ◽

Chemical Enrichment ◽

Abundance Patterns ◽

Solar Metallicity ◽

First Time

ABSTRACT The abundance patterns observed in the Sun and in metal-poor stars show a clear odd-even effect. An important question is whether the odd-even effect in solar-metallicity stars is similar to the Sun, or if there are variations that can tell us about different chemical enrichment histories. In this work, we report for the first time observational evidence of a differential odd-even effect in the solar twin HIP 11915, relative to the solar odd-even abundance pattern. The spectra of this star were obtained with high-resolving power (140 000) and signal-to-noise ratio (∼420) using the ESPRESSO spectrograph and the VLT telescope. Thanks to the high spectral quality, we obtained extremely precise stellar parameters (σ(Teff) = 2 K, $\sigma (\rm {[Fe/H]})$ = 0.003 dex, and σ(log g) = 0.008 dex). We determine the chemical abundance of 20 elements (Z ≤ 39) with high precision (∼0.01 dex), which shows a strong pattern of the odd-even effect even after performing galactic chemical evolution corrections. The odd-even effect is reasonably well-reproduced by a core-collapse supernova of 13 $\rm {M_{\odot }}$ and metallicity Z = 0.001 diluted into a metal-poor gas of 1 $\rm {M_{\odot }}$. Our results indicate that HIP 11915 has an odd-even effect slightly different than the Sun, thus confirming a different supernova enrichment history.

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Mono-enriched stars and Galactic chemical evolution

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038805 ◽

2020 ◽

Vol 643 ◽

pp. A49

Author(s):

C. J. Hansen ◽

A. Koch ◽

L. Mashonkina ◽

M. Magg ◽

M. Bergemann ◽

...

Keyword(s):

Chemical Evolution ◽

Second Generation ◽

Asymptotic Giant Branch ◽

Three Dimensional Model ◽

First Stars ◽

Abundance Pattern ◽

Abundance Patterns ◽

The Galaxy ◽

Bona Fide ◽

R Process

A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are excellent tracers as they preserve the abundance pattern of the gas from which they were born, and hence they are frequently targeted in chemical tagging studies. Here, we use a sample of 14 metal-poor stars observed with the high-resolution spectrograph called the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) to derive abundances of 32 elements (34 including upper limits). We present well-sampled abundance patterns for all stars obtained using local thermodynamic equilibrium (LTE) radiative transfer codes and one-dimensional (1D) hydrostatic model atmospheres. However, it is currently well-known that the assumptions of 1D and LTE may hide several issues, thereby introducing biases in our interpretation as to the nature of the first stars and the chemical evolution of the Galaxy. Hence, we use non-LTE (NLTE) and correct the abundances using three-dimensional model atmospheres to present a physically more reliable pattern. In order to infer the nature of the first stars, we compare unevolved, cool stars, which have been enriched by a single event (“mono-enriched”), with a set of yield predictions to pin down the mass and energy of the Pop III progenitor. To date, only few bona fide second generation stars that are mono-enriched are known. A simple χ2-fit may bias our inferred mass and energy just as much as the simple 1D LTE abundance pattern, and we therefore carried out our study with an improved fitting technique considering dilution and mixing. Our sample presents Carbon Enhanced Metal-Poor (CEMP) stars, some of which are promising bona fide second generation (mono-enriched) stars. The unevolved, dwarf BD+09_2190 shows a mono-enriched signature which, combined with kinematical data, indicates that it moves in the outer halo and likely has been accreted onto the Milky Way early on. The Pop III progenitor was likely of 25.5 M⊙ and 0.6 foe (0.6 1051 erg) in LTE and 19.2 M⊙ and 1.5 foe in NLTE, respectively. Finally, we explore the predominant donor and formation site of the rapid and slow neutron-capture elements. In BD-10_3742, we find an almost clean r-process trace, as is represented in the star HD20, which is a “metal-poor Sun benchmark” for the r-process, while TYC5481-00786-1 is a promising CEMP-r/-s candidate that may be enriched by an asymptotic giant branch star of an intermediate mass and metallicity.

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Abundance patterns and the chemical enrichment of nearby dwarf galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310000608 ◽

2009 ◽

Vol 5 (S265) ◽

pp. 219-226 ◽

Cited By ~ 1

Author(s):

Vanessa Hill

Keyword(s):

Star Formation ◽

Chemical Abundance ◽

Chemical Abundances ◽

First Stars ◽

Potential Wells ◽

Dwarf Spheroidal Galaxies ◽

Massive Galaxies ◽

Chemical Enrichment ◽

Abundance Patterns ◽

Spheroidal Galaxies

AbstractAs the least massive galaxies we know, dwarf spheroidal galaxies (dSph) allow to probe chemical enrichement on the smallest scales, and perhaps in its simplest expression. Particularly interesting are the issues concerning the efficency with which metals are retained or lost in these shallow potential wells (supernovae feedback), and the effect of this on star formation itself. Another fundamental issue concerns the earliest epochs of star formation: are first stars formed in similar ways and proportions in all halos ? Finally, as the smallest galaxies know, dSph have been suggested to be the surviving cousins of galaxy building blocs that (in λ-CDM) assemble to make larger galaxies. This parenthood would not necessarily hold at all late times, when survivors have lived their own differentiated life, but is expected at least at the earliest epochs.I review here the chemical abundances of individual stars in the nearest dwarf spheroidal galaxies, that have become available in increasing numbers (sample size and galaxies probed) in the last decade. Special emphasis is given to: a) recent results obtain with FLAMES on VLT, highlighting the power of detailed chemical abundance patterns of large samples of stars to unravel the various evolutionnary paths followed by dSph; b) the oldest and most metal-poor populations in dSph.

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Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

International Astronomical Union Colloquium ◽

10.1017/s0252921100080520 ◽

1976 ◽

Vol 32 ◽

pp. 169-182

Author(s):

B. Kuchowicz

Keyword(s):

Nuclear Physics ◽

Nuclear Reactions ◽

Chemical Elements ◽

Fission Products ◽

Abundance Pattern ◽

Isotopic Shifts ◽

Processed Material ◽

R Process ◽

Ap Stars ◽

Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

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