scholarly journals Primeval oxygen overabundance and type I-1/2 supernovae

1984 ◽  
Vol 105 ◽  
pp. 577-578
Author(s):  
F. Matteucci ◽  
A. Tornambé
Keyword(s):  
Chemical Evolution ◽  
Stellar Population ◽  
Type I ◽  
Chemical Enrichment ◽  
The Galaxy

Models of chemical evolution of the Galaxy have been computed by taking into account the different roles played by TypeI-1/2 (single stars suffering degenerate C-ignition) and Typell supernovae in the chemical enrichment. The overabundance of oxygen observed in the Halo stellar population has been well reproduced.

scholarly journals Chemical evolution of the Galaxy disk in connection with large-scale winds

2008 ◽  
Vol 4 (S254) ◽  
pp. 393-398
Author(s):  
Takuji Tsujimoto ◽  
Joss Bland-Hawthorn ◽  
Kenneth C. Freeman
Keyword(s):  
Chemical Evolution ◽  
Large Scale ◽  
Solar Neighborhood ◽  
Elemental Abundance ◽  
Abundance Gradient ◽  
Chemical Enrichment ◽  
Outer Disk ◽  
The Galaxy ◽  
Galaxy Disk ◽  
Set Up

AbstractComparison of elemental abundance features between old and young thin disk stars may reveal the action of ravaging winds from the Galactic bulge, which once enriched the whole disk, and set up the steep abundance gradient in the inner disk (RGC ≲ 10–;12 kpc) and simultaneously the metallicity floor ([Fe/H]~ −0.5) in the outer disk. After the end of a crucial influence by winds, chemical enrichment through accretion of a metal-poor material from the halo onto the disk gradually reduced the metallicity of the inner region, whereas an increase in the metallicity proceeded beyond a solar circle. This results in a flattening of abundance gradient in the inner disk, and our chemical evolution models confirm this mechanism for a flattening, which is in good agreement with the observations. Our scenario also naturally explains an observed break in the metallicity floor of the outer disk by young stars since the limit of self-enrichment in the outer disk is supposed to be [Fe/H]≲ −1 and inevitably incurs a direct influence of the dilution by a low-metal infall whose metallicity is [Fe/H]~ −1. Accordingly, we propose that the enrichment by large-scale winds is a crucial factor for chemical evolution of the disk, and claim to reconsider the models thus far for the disk including the solar neighborhood, in which the metallicity is predicted to monotonously increase with time. Furthermore, we anticipate that a flattening of abundance gradient together with a metal-rich floor in the outer disk are the hallmark of disk galaxies with significant central bulges.

scholarly journals Galactic Chemical Evolution in the Context of the Recently Revealed SNe Ia Delay Time Distribution

2011 ◽  
Vol 7 (S281) ◽  
pp. 251-252
Author(s):  
Takuji Tsujimoto
Keyword(s):  
Chemical Evolution ◽  
Delay Time ◽  
Time Distribution ◽  
Chemical Properties ◽  
Thin Disk ◽  
Chemical Enrichment ◽  
Precise Knowledge ◽  
The Galaxy ◽  
Type Ia ◽  
Ia Supernovae

AbstractThe Galaxy is composed of four distinct structures, i.e., halo, bulge, and thick and thin disks, that are formed and evolved on different timescales; thus accordingly the speeds of chemical enrichment are different from one another, which is imprinted in individual stellar abundances. To decipher them, precise knowledge of the timing of the release of nucleosynthesis materials from various production sites is critical. The delay time distribution (DTD) of Type Ia supernovae (SNe Ia), recently revealed by the SNe Ia surveys of external galaxies, is incorporated into the models of chemical evolution for each structure. Here we report that the observed chemical properties for the thin and thick disks are compatible with a new SNe Ia DTD, and suggests a close chemical connection between the two in the way that the thin disk is formed from gas left after thick disk formation. This nicely explains the lack of thin disk stars with [Fe/H] ≲ −0.8. In this new context, a top-heavy IMF for the bulge is firmly confirmed. Finally we discuss the possibility of some modification of the DTD that might be considered for the halo case.

Final Remarks: Connections between Chemical and Dynamical Evolution

1977 ◽  
Vol 45 ◽  
pp. 309-319
Author(s):  
Beatrice M. Tinsley
Keyword(s):  
Interstellar Medium ◽  
Chemical Evolution ◽  
Dynamical Evolution ◽  
Theoretical Background ◽  
Dynamical Processes ◽  
Chemical Enrichment ◽  
The Galaxy ◽  
History Of

Dynamical processes strongly affect the chemical enrichment of gas in galaxies, so abundances in stars and the Interstellar medium can be used as probes of the dynamical history of the Galaxy. By way of tying together some diverse points, rather than summarizing the conference, I shall discuss some examples of connections between chemical and dynamical evolution. The first section of this paper mentions some of the well-known ways in which dynamical processes can affect chemical evolution, in order to outline a theoretical background to the use of abundances as clues to dynamics.

scholarly journals Planetary Nebulae and the Chemical Evolution of Galaxies

1983 ◽  
Vol 103 ◽  
pp. 463-472 ◽  
Author(s):  
Alfonso Serrano
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Low Mass Stars ◽  
Chemical Enrichment ◽  
The Past ◽  
The Galaxy ◽  
History Of ◽  
Low Mass

Tinsley (1978) has done an excellent review that illustrates the methods and concepts that can be developed to assess the effects of planetary nebulae (PN) on the long-term history of the galaxy. Tinsley concluded that research in PN could put constraints on the past rate of star formation and provide information on chemical enrichment by low mass stars.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

scholarly journals LINER-like emission in red galaxies: evolutionary phase or recurring phenomenon?

2007 ◽  
Vol 3 (S245) ◽  
pp. 181-184
Author(s):  
Genevieve J. Graves
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Large Fraction ◽  
Optical Emission ◽  
Ionized Gas ◽  
Satellite Galaxy ◽  
The Galaxy ◽  
Evolutionary Phase ◽  
Interstellar Material ◽  
Red Galaxies

AbstractWe present recent results showing that a large fraction of red sequence galaxies contain ionized gas with LINER-like optical emission line ratios. This emission is more frequently found in galaxies with lower central velocity dispersion (σ) and these galaxies typically have younger mean ages than galaxies at the same σ which do not host emission. We suggest that the presence of LINER-like emission may be determined by the quantity of interstellar material in these galaxies and may be associated with the recent accretion of a gas-rich satellite galaxy or alternatively with stellar mass loss that declines as the galaxy stellar population ages.

scholarly journals The Evolution of 3He, 4He and D in the Galaxy

2000 ◽  
Vol 198 ◽  
pp. 540-546 ◽  
Author(s):  
Cristina Chiappini ◽  
Francesca Matteucci
Keyword(s):  
Chemical Evolution ◽  
Present Model ◽  
Galactic Disk ◽  
The Sun ◽  
Mixing Process ◽  
Low Mass Stars ◽  
A Value ◽  
The Galaxy ◽  
Low Mass ◽  
Standing Problem

In this work we present the predictions of a modified version of the ‘two-infall model’ (Chiappini et al. 1997 - CMG) for the evolution of 3He, 4He and D in the solar vicinity, as well as their distributions along the Galactic disk. In particular, we show that when allowing for extra-mixing process in low mass stars (M < 2.5 M⊙), as predicted by Charbonnel and do Nascimento (1998), a long standing problem in chemical evolution is solved, namely: the overproduction of 3He by the chemical evolution models as compared to the observed values in the sun and in the interstellar medium. Moreover, we show that chemical evolution models can constrain the primordial value of the deuterium abundance and that a value of (D/H)p < 3 × 10—5 is suggested by the present model. Finally, adopting the primordial 4He abundance suggested by Viegas et al. (1999), we obtain a value for ΔY/ΔZ ≃ 2 and a better agreement with the solar 4He abundance.

scholarly journals Moving translational mass spectrometry imaging towards transparent and reproducible data analyses: A case study of an urothelial cancer cohort analyzed in the Galaxy framework

2021 ◽  
Author(s):  
Melanie Christine Föll ◽  
Veronika Volkmann ◽  
Kathrin Enderle-Ammour ◽  
Konrad Wilhelm ◽  
Dan Guo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Data Analysis ◽  
Mass Spectrometry Imaging ◽  
Urothelial Cancer ◽  
Type I ◽  
Raw Data ◽  
The Galaxy ◽  
Muscle Invasive ◽  
Reproducible Manner

Background: Mass spectrometry imaging (MSI) derives spatial molecular distribution maps directly from clinical tissue specimens. This allows for spatial characterization of molecular compositions of different tissue types and tumor subtypes, which bears great potential for assisting pathologists with diagnostic decisions or personalized treatments. Unfortunately, progress in translational MSI is often hindered by insufficient quality control and lack of reproducible data analysis. Raw data and analysis scripts are rarely publicly shared. Here, we demonstrate the application of the Galaxy MSI tool set for the reproducible analysis of an urothelial carcinoma dataset. Methods: Tryptic peptides were imaged in a cohort of 39 formalin-fixed, paraffin-embedded human urothelial cancer tissue cores with a MALDI-TOF/TOF device. The complete data analysis was performed in a fully transparent and reproducible manner on the European Galaxy Server. Annotations of tumor and stroma were performed by a pathologist and transferred to the MSI data to allow for supervised classifications of tumor vs. stroma tissue areas as well as for muscle-infiltrating and non-muscle invasive urothelial carcinomas. For putative peptide identifications, m/z features were matched to the MSiMass list. Results: Rigorous quality control in combination with careful pre-processing enabled reduction of m/z shifts and intensity batch effects. High classification accuracy was found for both, tumor vs. stroma and muscle-infiltrating vs. non-muscle invasive tumors. Some of the most discriminative m/z features for each condition could be assigned a putative identity: Stromal tissue was characterized by collagen type I peptides and tumor tissue by histone and heat shock protein beta-1 peptides. Intermediate filaments such as cytokeratins and vimentin were discriminative between the tumors with different muscle-infiltration status. To make the study fully reproducible and to advocate the criteria of FAIR (findability, accessibility, interoperability, and reusability) research data, we share the raw data, spectra annotations as well as all Galaxy histories and workflows. Data are available via ProteomeXchange with identifier PXD026459 and Galaxy results via https://github.com/foellmelanie/Bladder_MSI_Manuscript_Galaxy_links. Conclusion: Here, we show that translational MSI data analysis in a fully transparent and reproducible manner is possible and we would like to encourage the community to join our efforts.

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