scholarly journals Chemodynamical History of the Galactic Bulge

2018 ◽  
Vol 56 (1) ◽  
pp. 223-276 ◽  
Author(s):  
Beatriz Barbuy ◽  
Cristina Chiappini ◽  
Ortwin Gerhard
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Stellar Populations ◽  
Observational Evidence ◽  
Galactic Bulge ◽  
Large Samples ◽  
Self Consistent ◽  
History Of ◽  
Bulge Formation ◽  
And Chemical Properties

The Galactic Bulge can uniquely be studied from large samples of individual stars and is therefore of prime importance for understanding the stellar population structure of bulges in general. Here the observational evidence on the kinematics, chemical composition, and ages of Bulge stellar populations based on photometric and spectroscopic data is reviewed. The bulk of Bulge stars are old and span a metallicity range of −1.5≲[Fe/H]≲+0.5. Stellar populations and chemical properties suggest a star-formation timescale below ∼2 Gyr. The overall Bulge is barred and follows cylindrical rotation, and the more metal-rich stars trace a box/peanut (B/P) structure. Dyna-mical models demonstrate the different spatial and orbital distributions of metal-rich and metal-poor stars. We discuss current Bulge-formation scenarios based on dynamical, chemical, chemodynamical, and cosmological models. Despite impressive progress, we do not yet have a successful fully self-consistent chemodynamical Bulge model in the cosmological framework, and we will also need a more extensive chrono-chemical-kinematic 3D map of stars to better constrain such models.

scholarly journals Stellar parameters in the bulge cluster NGC 6553

1997 ◽  
Vol 189 ◽  
pp. 203-206 ◽  
Author(s):  
B. Barbuy ◽  
S. Ortolani ◽  
E. Bica ◽  
A. Renzini ◽  
M.D. Guarnieri
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Spectroscopic Analysis ◽  
Galactic Center ◽  
Stellar Populations ◽  
The Sun ◽  
Galactic Bulge ◽  
Complete Understanding ◽  
Luminosity Functions ◽  
Bulge Formation

Globular clusters in the Galactic bulge form a flattened system, extending from the Galactic center to about 4.5 kpc from the Sun (Barbuy et al. 1997). A study of abundance ratios in these clusters is very important for a more complete understanding of the bulge formation. In this work we present a spectroscopic analysis of individual stars in NGC 6553. This cluster is a key one because it is located at d⊙ ≍ 5.1 kpc, therefore relatively close to us, and at the same time it is representative of the Galactic bulge stellar population: (a) Ortolani et al. (1995) showed that NGC 6553 and NGC 6528 show very similar Colour-Magnitude Diagrams (CMDs), and NGC 6528 is located at d⊙ ≍ 7.83 kpc, very close to the Galactic center; (b) the stellar populations of the Baade Window is also very similar to that of NGC 6553 and NGC 6528 as Ortolani et al. (1995) have shown by comparing their luminosity functions.

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 Shaping Disk Galaxy Stellar Populations via Internal and External Processes

2012 ◽  
Vol 10 (H16) ◽  
pp. 372-372
Author(s):  
Rok Roškar
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Stellar Populations ◽  
Radial Migration ◽  
Disk Formation ◽  
Process Understanding ◽  
History Of ◽  
Nearby Galaxies ◽  
Gas Accretion

AbstractIn recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

scholarly journals Star Clusters in Local Group Galaxies

1995 ◽  
Vol 164 ◽  
pp. 181-192
Author(s):  
Edward W. Olszewski
Keyword(s):  
Stellar Population ◽  
Local Group ◽  
Star Clusters ◽  
Stellar Populations ◽  
Cluster Systems ◽  
Star Forming ◽  
Long Time ◽  
History Of ◽  
Individual Objects

In this paper I will try to give the flavor of two different concepts of stellar population, namely, the population of cluster systems within galaxies, and the stellar populations within individual clusters. I hope to show, in concert with other papers in this volume, that a generic vision of Population I and II has been outdated for a long time. I believe that it is still proper to talk about populations within individual objects; in the case of galaxies, one might make a correspondence of populations with the important star forming events in the history of a galaxy.

Nuclear and chemical characterization of heavy actinides

2019 ◽  
Vol 107 (9-11) ◽  
pp. 803-819
Author(s):  
Yuichiro Nagame
Keyword(s):  
Recent Progress ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Nuclear Fission ◽  
Heavy Nuclei ◽  
Nuclear Decay ◽  
Decay Properties ◽  
History Of ◽  
And Chemical Properties

Abstract Recent progress in the production of heavy nuclei far from stability and in the studies of nuclear and chemical properties of heavy actinides is briefly reviewed. Exotic nuclear decay properties including nuclear fission of heavy nuclei, measurements of first ionization potentials of heavy actinides, and redox studies of heavy actinides are described. Brief history of discovery of the transuranium elements is also presented.

scholarly journals Binary fraction indicators in resolved stellar populations and supernova-type ratios

2020 ◽  
Vol 497 (2) ◽  
pp. 2201-2212 ◽  
Author(s):  
E R Stanway ◽  
J J Eldridge ◽  
A A Chrimes
Keyword(s):  
Massive Star ◽  
Stellar Population ◽  
Stellar Populations ◽  
Initial Mass ◽  
Core Collapse ◽  
Population Synthesis ◽  
Large Samples ◽  
Low Mass ◽  
Galaxy Population ◽  
Number Counts

ABSTRACT The binary fraction of a stellar population can have pronounced effects on its properties, and, in particular, the number counts of different massive star types, and the relative subtype rates of the supernovae (SNe) that end their lives. Here we use binary population synthesis models with a binary fraction that varies with initial mass to test the effects on resolved stellar pops and SNe, and ask whether these can constrain the poorly-known binary fraction in different mass and metallicity regimes. We show that Wolf–Rayet (WR) star subtype ratios are valuable binary diagnostics, but require large samples to distinguish by models. Uncertainties in which stellar models would be spectroscopically classified as WR stars are explored. The ratio of thermonuclear, stripped-envelope, and other core-collapse SNe may prove a more accessible test and upcoming surveys will be sufficient to constrain both the high- and low-mass binary fraction in the z < 1 galaxy population.

PROPERTIES AND EFFECTS OF NONPETROLEUM OILS

1975 ◽  
Vol 1975 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Hans J. Crump-Wiesner ◽  
Allen L. Jennings
Keyword(s):  
Pollution Control ◽  
Environmental Protection Agency ◽  
Oil Spills ◽  
Chemical Properties ◽  
Protection Agency ◽  
Legislative History ◽  
History Of ◽  
Physical And Chemical ◽  
Petroleum Oil ◽  
And Chemical Properties

ABSTRACT Legislative history of water pollution control has not included detailed scientific definitions of what is meant by the rather inclusive term “oil.” Because of the publicity surrounding spills of crude or petroleum-derived oils, little attention has been focused on non-petroleum oils. Approximately 5% of the oil spills reported to the Environmental Protection Agency are nonpetroleum oils. Their physical and chemical properties and adverse environmental effects are strikingly similar to the behavior of petroleum oil in the aquatic environment. This paper presents a comparative analysis of the properties and effects of petroleum versus nonpetroleum oils. Their similarities prove that these oils should be treated as one entity regardless of their origin. Finally, additional guidelines are presented to provide a more broadly applicable distinction between oil and other hazardous materials for enforcement purposes.

scholarly journals Stellar population synthesis: Application To Galactic Bulges

1993 ◽  
Vol 153 ◽  
pp. 133-150
Author(s):  
N. Arimoto
Keyword(s):  
Observational Data ◽  
Stellar Population ◽  
Stellar Populations ◽  
Population Synthesis ◽  
Firm Conclusion ◽  
Formation History ◽  
Stellar Population Synthesis ◽  
Central Regions ◽  
History Of ◽  
Metallicity Distribution

The stellar populations give traces of the formation history of the bulges. The metallicity distribution of K-giants in the Galactic bulge resembles to that of the giant ellipticals. There seems to be no conspicuous colour-magnitude relation intrinsic to the bulges. This can be explained if the bulges formed by the dissipative collapse of central regions of proto-galaxies followed by the supernova-driven bulge wind which was induced later than the dwarf ellipticals of the similar mass (the biased wind). Unfortunately, the observational data available at present of stellar populations of the bulges are not yet sufficient to get a firm conclusion on the origin of the bulges.

scholarly journals Stellar Populations in High-z Galaxy Mergers

1999 ◽  
Vol 186 ◽  
pp. 202-202
Author(s):  
Yasuhiro Shioya ◽  
Kenji Bekki
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Stellar Populations ◽  
Star Formation History ◽  
Galaxy Mergers ◽  
Formation History ◽  
Self Consistent ◽  
Consistent Manner ◽  
History Of ◽  
The Difference

We investigate the nature of stellar populations of major galaxy mergers between late-type spirals considerably abundant in interstellar medium by performing numerical simulations designed to solve both the dynamical and chemical evolution in a self-consistent manner. We particularly consider that the star formation history of galaxy mergers is a crucial determinant for the nature of stellar populations of merger remnants, and therefore investigate how the difference in star formation history between galaxy mergers affects the chemical evolution of galaxy mergers.

Sign in / Sign up

Export Citation Format

Share Document