The Metallicity Distribution Function of Halo Dwarfs and Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 517-518
Author(s):  
J. B. Laird ◽  
M. P. Rupin ◽  
B. W. Carney ◽  
D. W. Latham ◽  
R. L. Kurucz
Keyword(s):  
Distribution Function ◽  
Simple Model ◽  
Chemical Evolution ◽  
Globular Clusters ◽  
Dwarf Stars ◽  
Metallicity Distribution

Metallicities have been determined for a chemically unbiased sample of field halo dwarf stars. Their metallicity distribution function is similar to the predictions of a simple model of chemical evolution, but somewhat different from that of globular clusters.

scholarly journals Are the globular clusters with significant internal [Fe/H] spreads all former dwarf galaxy nuclei?

2015 ◽  
Vol 11 (S317) ◽  
pp. 110-115 ◽  
Author(s):  
G. S. Da Costa
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Density Profiles ◽  
Cluster Density ◽  
Galactic Globular Clusters ◽  
Metallicity Distribution

AbstractIn this contribution the hypothesis that the Galactic globular clusters with substantial internal [Fe/H] abundance ranges are the former nuclei of disrupted dwarf galaxies is discussed. Evidence considered includes the form of the metallicity distribution function, the occurrence of large diffuse outer envelopes in cluster density profiles, and the presence of ([s-process/Fe], [Fe/H]) correlations. The hypothesis is shown to be plausible but with the caveat that if significantly more than the current nine clusters known to have [Fe/H] spreads are found, then re-evaluation will be required.

scholarly journals Blanco DECam Bulge Survey (BDBS) II: project performance, data analysis, and early science results

2020 ◽  
Vol 499 (2) ◽  
pp. 2357-2379
Author(s):  
Christian I Johnson ◽  
Robert Michael Rich ◽  
Michael D Young ◽  
Iulia T Simion ◽  
William I Clarkson ◽  
...  
Keyword(s):  
Distribution Function ◽  
Dark Energy ◽  
Globular Clusters ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture ◽  
Project Performance ◽  
Point Spread ◽  
Spread Function ◽  
Red Clump ◽  
Metallicity Distribution

ABSTRACT The Blanco DECam Bulge Survey (BDBS) imaged more than 200 sq deg of the Southern Galactic bulge using the ugrizY filters of the Dark Energy Camera, and produced point spread function photometry of approximately 250 million unique sources. In this paper, we present details regarding the construction and collation of survey catalogues, and also discuss the adopted calibration and dereddening procedures. Early science results are presented with a particular emphasis on the bulge metallicity distribution function and globular clusters. A key result is the strong correlation (σ ∼ 0.2 dex) between (u − i)o and [Fe/H] for bulge red clump giants. We utilized this relation to find that interior bulge fields may be well described by simple closed box enrichment models, but fields exterior to b ∼ −6° seem to require a secondary metal-poor component. Applying scaled versions of the closed box model to the outer bulge fields is shown to significantly reduce the strengths of any additional metal-poor components when compared to Gaussian mixture models. Additional results include: a confirmation that the u band splits the subgiant branch in M22 as a function of metallicity, the detection of possible extratidal stars along the orbits of M 22 and FSR 1758, and additional evidence that NGC 6569 may have a small but discrete He spread, as evidenced by red clump luminosity variations in the reddest bands. We do not confirm previous claims that FSR 1758 is part of a larger extended structure.

scholarly journals The Pristine Survey – VIII. The metallicity distribution function of the Milky Way halo down to the extremely metal-poor regime

2020 ◽  
Vol 492 (4) ◽  
pp. 4986-5002 ◽  
Author(s):  
K Youakim ◽  
E Starkenburg ◽  
N F Martin ◽  
G Matijevič ◽  
D S Aguado ◽  
...  
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Milky Way ◽  
Current Data ◽  
Low Latitude ◽  
Chemical Enrichment ◽  
Merger Event ◽  
Low Metallicity ◽  
Metallicity Distribution ◽  
Milky Way Halo

ABSTRACT The Pristine survey uses narrow-band photometry to derive precise metallicities down to the extremely metal-poor regime ($ \rm [Fe/H] \lt -3$), and currently consists of over 4 million FGK-type stars over a sky area of $\sim 2500\, \mathrm{deg}^2$. We focus our analysis on a subsample of ∼80 000 main-sequence turn-off stars with heliocentric distances between 6 and 20 kpc, which we take to be a representative sample of the inner halo. The resulting metallicity distribution function (MDF) has a peak at $ \rm [Fe/H] =-1.6$, and a slope of Δ(LogN)/$\Delta \rm [Fe/H] = 1.0 \pm 0.1$ in the metallicity range of $-3.4\; \lt\; \rm [Fe/H]\; \lt -2.5$. This agrees well with a simple closed-box chemical enrichment model in this range, but is shallower than previous spectroscopic MDFs presented in the literature, suggesting that there may be a larger proportion of metal-poor stars in the inner halo than previously reported. We identify the Monoceros/TriAnd/ACS/EBS/A13 structure in metallicity space in a low-latitude field in the anticentre direction, and also discuss the possibility that the inner halo is dominated by a single, large merger event, but cannot strongly support or refute this idea with the current data. Finally, based on the MDF of field stars, we estimate the number of expected metal-poor globular clusters in the Milky Way halo to be 5.4 for $ \rm [Fe/H]\; \lt\; -2.5$ and 1.5 for $ \rm [Fe/H]\; \lt\; -3$, suggesting that the lack of low-metallicity globular clusters in the Milky Way is not due simply to statistical undersampling.

scholarly journals Globular Clusters and Field Halo Stars

1988 ◽  
Vol 126 ◽  
pp. 133-148
Author(s):  
Bruce W. Carney
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Chemical Properties ◽  
Elemental Abundance ◽  
Stellar Kinematics ◽  
Halo Stars ◽  
Abundance Patterns ◽  
Halo Population ◽  
Metallicity Distribution ◽  
And Chemical Properties

Recent work on the chemistry and kinematics of the field halo population stars is reviewed, including the metallicity distribution function, elemental abundance patterns, primordial abundances, and their relations with stellar kinematics. The important role played by these stars in determining the ages of the globular clusters is discussed. A comparison is made between the kinematic and chemical properties of the field and cluster stars to ascertain if they share a common history.

scholarly journals Deriving the Metallicity Distribution Function of Galactic Systems

2003 ◽  
Vol 20 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Yeshe Fenner ◽  
Brad K. Gibson
Keyword(s):  
Distribution Function ◽  
Star Formation ◽  
Chemical Evolution ◽  
Thin Disk ◽  
Star Formation History ◽  
Dual Phase ◽  
Formation History ◽  
Stellar Halo ◽  
Star Formation Histories ◽  
Metallicity Distribution

AbstractThe chemical evolution of the Milky Way is investigated using a dual-phase metal-enriched infall model in which primordial gas fuels the earliest epoch of star formation, followed by the ongoing formation of stars from newly accreted gas. The latest metallicity distribution of local K-dwarfs is reproduced by this model, which allows the Galactic thin disk to form from slightly metal-enriched gas with α-element enhancement. Our model predicts ages for the stellar halo and thin disk of 12.5 and 7.4 Gyr respectively, in agreement with empirically determined values. The model presented in this paper is compared with a similar dual-phase infall model from Chiappini et al. (2001). We discuss a degeneracy that enables both models to recover the K-dwarf metallicity distribution while yielding different star formation histories.The metallicity distribution function (MDF) of K-dwarfs is proposed to be more directly comparable to chemical evolution model results than the G-dwarf distribution because lower mass K-dwarfs are less susceptible to stellar evolutionary effects. The K-dwarf MDF should consequently be a better probe of star formation history and provide a stronger constraint to chemical evolution models than the widely used G-dwarf MDF. The corrections that should be applied to a G-dwarf MDF are quantified for the case of the outer halo of NGC 5128.

scholarly journals A construction of the general relativistic Boltzmann equation

1984 ◽  
Vol 7 (3) ◽  
pp. 591-597 ◽  
Author(s):  
P. Dolan ◽  
A. C. Zenios
Keyword(s):  
Distribution Function ◽  
Boltzmann Equation ◽  
Kinetic Equation ◽  
Simple Model ◽  
State Space ◽  
Differential Forms ◽  
Relativistic Boltzmann Equation ◽  
Dimensional State Space ◽  
General Relativistic ◽  
Invariant Differential

Our work depends essentially on the notion of a one-particle seven-dimensional state-space. In constructing a general relativistic theory we assume that all measurable quantities arise from invariant differential forms. In this paper, we study only the case when instantaneous, binary, elastic collisions occur between the particles of the gas. With a simple model for colliding particles and their collisions, we derive the kinetic equation, which gives the change of the distribution function along flows in state-space.

scholarly journals The Bologna Open Cluster Chemical Evolution project: a large, homogeneous sample of Galactic open clusters

2008 ◽  
Vol 4 (S258) ◽  
pp. 153-160
Author(s):  
Angela Bragaglia
Keyword(s):  
Chemical Evolution ◽  
Galactic Disk ◽  
Open Cluster ◽  
Open Clusters ◽  
Photometric Data ◽  
Homogeneous Sample ◽  
Metallicity Distribution

AbstractThe Bologna Open Cluster Chemical Evolution (BOCCE) project is a photometric and spectroscopic survey of open clusters, to be used as tracers of the Galactic disk properties and evolution. The clusters parameters (age, distance, reddening, metallicity, and detailed abundances) are derived in a precise and homogeneous way. This will contribute to a solid, reliable description of the disk: the clusters parameters will be used, for instance, to determine the metallicity distribution in the Galactic disk and how it has evolved with time. We have concentrated on old open clusters and we have presently in our hands data for about 40 open clusters; we have fully analyzed the photometric data for about one half of them and the spectra for one quarter of them.

Globular clusters and their link with stellar populations in the Milky Way

2019 ◽  
Vol 14 (S351) ◽  
pp. 19-23
Author(s):  
David Yong
Keyword(s):  
Chemical Evolution ◽  
Globular Clusters ◽  
Milky Way ◽  
Star Clusters ◽  
Stellar Populations ◽  
Chemical Compositions ◽  
Chemical Abundance ◽  
Chemical Enrichment ◽  
Similarities And Differences ◽  
Insight Into

AbstractObservations of stellar chemical compositions enable us to identify connections between globular clusters and stellar populations in the Milky Way. In particular, chemical abundance ratios provide detailed insight into the chemical enrichment histories of star clusters and the field populations. For some elements, there are striking differences between field and cluster stars which reflect different nucleosynthetic processes and/or chemical evolution. The goal of this talk was to provide an overview of similarities and differences in chemical compositions between globular clusters and the Milky Way as well as highlighting a few areas for further examination.

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