scholarly journals The Chemical Evolution of the Galactic Halo and Disk

1987 ◽  
Vol 115 ◽  
pp. 701-703
Author(s):  
Federico Ferrini ◽  
Francesco Palla ◽  
Steven N. Shore
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Galactic Halo ◽  
Stellar Populations ◽  
Galactic Evolution ◽  
Formation Model ◽  
Present Epoch ◽  
The Galaxy ◽  
Metal Abundance ◽  
History Of

The history of star formation in our galaxy is written in the metal abundance distributions of the stellar populations. Any star formation model is constrained by two facts. First, there was a period in the early stages of galactic evolution during which the metallicity of the gas out of which stars were being formed was significantly lower than the present epoch. Second, there is a paucity of extremely metal deficient stars in the disk of the galaxy.

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.

scholarly journals The abundance distribution of [α/Fe] in the Galactic disk stars

2013 ◽  
Vol 9 (S298) ◽  
pp. 419-420
Author(s):  
Ji Li ◽  
Ruijuan Fu
Keyword(s):  
Statistical Analysis ◽  
Star Formation ◽  
Chemical Evolution ◽  
Galactic Disk ◽  
Abundance Ratio ◽  
Thick Disk ◽  
Abundance Distribution ◽  
Dwarf Stars ◽  
The Galaxy ◽  
History Of

AbstractThe abundance ratio [α/Fe] is a useful tracer to probe the history of star formation and the chemical evolution of the Galaxy. We present a statistical analysis of [α/Fe] in 953 dwarf stars to investigate the distributions of [α/Fe] in the the thin- and thick-disk stars.

scholarly journals Two distinct halo populations in the solar neighborhood: evidence from stellar abundance of beryllium

2013 ◽  
Vol 9 (S298) ◽  
pp. 83-85
Author(s):  
Kefeng Tan ◽  
Gang Zhao
Keyword(s):  
Star Formation ◽  
Galactic Halo ◽  
Formation Rate ◽  
Solar Neighborhood ◽  
Elemental Abundance ◽  
Star Formation History ◽  
Dwarf Stars ◽  
Formation History ◽  
The Galaxy ◽  
History Of

AbstractIt is now generally believed that the Galaxy was formed through hierarchical merging, which means that different components of the Galaxy may have experienced different chemical evolution histories. Since alpha elements are mainly produced by core collapse supernovae, they are closely associated with the star formation history of the Galaxy. In this regard, Galactic components with different alpha elemental abundance patterns may show different behaviors in beryllium abundances since the production of beryllium is correlated with the cosmic rays and thus the supernovae. A recent study by Nissen & Schuster (2010) has revealed the existence of two distinct halo populations in the solar neighborhood based on the alpha elemental abundances and kinematics of 94 dwarf stars. We determined beryllium abundances for some of these stars and find systematic differences in beryllium abundances between these two halo populations. Our results consolidate the conclusion of two distinct halo populations in the solar neighborhood. Our results also show that beryllium abundance is a very good indicator of star formation rate, and could be used to trace the substructures of the Galactic halo.

scholarly journals Kinematics and Dynamics of the Magellanic Clouds

1984 ◽  
Vol 108 ◽  
pp. 107-114
Author(s):  
K. C. Freeman
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Magellanic Clouds ◽  
Star Formation History ◽  
Kinematics And Dynamics ◽  
List Type ◽  
Formation History ◽  
The Galaxy ◽  
History Of ◽  
Magellanic Stream

Why are the kinematics and dynamics of the Magellanic Clouds worth studying ? Some of the reasons are: 1.The Clouds are the closest examples of Magellanic systems. These asymmetric systems give some interesting dynamical problems. Because the Clouds are so close, a unique amount of information can be obtained on the kinematics of objects of all ages. This should be very helpful for understanding the dynamics.2.The Clouds and the Galaxy are interacting. This produces complex kinematics of the gas in and between the Clouds, and also the Magellanic Stream. Again, very detailed information can be derived. We would like to know enough about the gas dynamics of interacting galaxies, to be able to explain the kinematics produced by this interaction.3.The interaction will affect the star formation and chemical evolution in the Clouds. As new results are obtained on the star formation history and the chemical evolution, it is important to follow in parallel the dynamical history of the system, to see if the dynamics, star formation and chemical evolution can be tied together.

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.

scholarly journals Galactic evolution and the two-colour diagram

1964 ◽  
Vol 20 ◽  
pp. 37-37
Author(s):  
R. H. Stoy
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Past History ◽  
Photometric Data ◽  
Galactic Evolution ◽  
The Past ◽  
The Galaxy ◽  
History Of ◽  
Present Distribution ◽  
Metal Abundances

Information about the past history of the Galaxy may be obtained from a two-colour diagram, since the present distribution of stars in such a diagram depends on the past rate of star formation and the past metal abundances in the interstellar medium. As an illustration of this, I would like to discuss three diagrams that were recently prepared by Dr. M. E. Dixon from Cape photometric data (Dixon 1963a,b).

scholarly journals HERMES – An instrument of the future

2009 ◽  
Vol 5 (S262) ◽  
pp. 448-449 ◽  
Author(s):  
Elizabeth Wylie-de Boer ◽  
Kenneth Freeman
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Resolving Power ◽  
Individual Stars ◽  
Elemental Abundances ◽  
The Future ◽  
The Galaxy ◽  
History Of ◽  
High Resolution Spectrometer ◽  
Resolution Spectrometer

AbstractHERMES is a new, multi-object high resolution spectrometer for the 3.9m Anglo Australian Telescope, using the existing 2dF positioner. The primary goal of the HERMES survey is to unravel the history of the Galaxy from detailed elemental abundances for about 1.2 million individual stars. The HERMES chemical tagging survey concentrates on the 5000 to 8000 Å window at a resolving power of 30,000 in order to identify dissolved star formation aggregates and ascertain the importance of mergers throughout the history of the Galaxy.

scholarly journals The evolution of massive galaxies in semi-analytical models of galaxy formation

2012 ◽  
Vol 8 (S295) ◽  
pp. 191-199
Author(s):  
Carlton M. Baugh
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Process ◽  
Hierarchical Models ◽  
Gravitational Instability ◽  
Stellar Populations ◽  
Analytical Models ◽  
Massive Galaxies ◽  
Current State ◽  
The Galaxy

AbstractMassive galaxies with old stellar populations have been put forwards as a challenge to models in which cosmic structures grow hierarchically through gravitational instability. I will explain how the growth of massive galaxies is helped by features of hierarchical models. I give a brief outline of how the galaxy formation process is modelled in hierarchical cosmologies using semi-analytical models, and illustrate how these models can be refined as our understanding of processes such as star formation improves. I then present a brief survey of the current state of play in the modelling of massive galaxies and list some outstanding challenges.

scholarly journals How to Model the Chemical Evolution of Galaxies

1993 ◽  
Vol 155 ◽  
pp. 557-566
Author(s):  
Joachim Köppen
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Time Scale ◽  
Life Time ◽  
Magellanic Clouds ◽  
Formation Time ◽  
List Type ◽  
The Galaxy ◽  
H Ii Region ◽  
Magellanic Stream

For a first interpretation of the comparison of observational data, the crude “Simple Model” of chemical evolution is quite useful. Since it has well been described in the literature (e.g. Pagel and Patchett 1975, Tinsley 1980), let us here just review the assumptions and whether they are satisfied: 1.The galaxy is a closed system, with no exchange of matter with its surroundings: For the solar neighbourhood this probably is not true (the infamous Gdwarf-“problem”, Pagel 1989b). For the Magellanic Clouds this is most certainly wrong, because of the presence of the Inter-Cloud Region and the Magellanic Stream, and evidence for interaction with each other and the Galaxy as well (cf. e.g. Westerlund 1990).2.It initially consists entirely of gas (without loss of generality of primordial composition): This is good approximation also for models with gas infall, as long as the infall occurs with a time scale shorter than the star formation time scale.3.The metal production of the average stellar generation (the yield y) is constant with time: Initially, it is reasonable to make this assumption. For tables of the oxygen yield see Koppen and Arimoto (1991).4.The metal rich gas ejected by the stars is completely mixed with the ambient gas. To neglect the finite stellar life times (“instantaneous recycling approximation”) is appropriate for elements synthesized in stars whose life time is much shorter than the star formation time scale, such as oxygen, neon, sulphur, and argon.5.The gas is well mixed at all times: We don't know. The dispersion of H II region abundances may give an indication. In the Magellanic Clouds Dufour (1984) finds quite a low value (±0.08 dex for oyxgen).

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