scholarly journals Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo

2007 ◽  
Vol 119 (859) ◽  
pp. 939-961 ◽  
Author(s):  
Doug Geisler ◽  
George Wallerstein ◽  
Verne V. Smith ◽  
Dana I. Casetti‐Dinescu
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Chemical Abundances

Chemical composition of globular clusters in dwarf galaxies

2019 ◽  
Vol 14 (S351) ◽  
pp. 317-320
Author(s):  
Søren S. Larsen
Keyword(s):  
Chemical Composition ◽  
Globular Clusters ◽  
Milky Way ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Chemical Abundances ◽  
Preliminary Results ◽  
Detailed Chemical

AbstractThis contribution gives an update on on-going efforts to characterise the detailed chemical abundances of Local Group globular clusters (GCs) from integrated-light spectroscopy. Observations of a sample of 20 GCs so far, located primarily within dwarf galaxies, show that at low metallicities the [α/Fe] ratios are generally indistinguishable from those in Milky Way GCs. However, the “knee” above which [α/Fe] decreases towards Solar-scaled values occurs at lower metallicities in the dwarfs, implying that GCs follow the same trends seen in field stars. Efforts are underway to establish NLTE corrections for integrated-light abundance measurements, and preliminary results for Mn are discussed.

scholarly journals Constraints on Interactions and Mergers from dSph Galaxies and Globular Clusters

1999 ◽  
Vol 186 ◽  
pp. 52-52
Author(s):  
E.K. Grebel
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Local Group ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Thick Disk ◽  
History Of

Observations at high redshifts are revealing numerous interactions and ongoing mergers. Our own Milky Way is currently merging with the Sagittarius dwarf spheroidal (dSph) galaxy. Past mergers with dwarf galaxies may have contributed significantly to the Galactic halo and possibly to the thick disk. The properties of Local Group dSphs and halo globular clusters impose constraints on the merger history of the Milky Way.

scholarly journals Formation of massive globular clusters with dark matter and its implication on dark matter annihilation

2020 ◽  
Vol 496 (1) ◽  
pp. L70-L74
Author(s):  
Henriette Wirth ◽  
Kenji Bekki ◽  
Kohei Hayashi
Keyword(s):  
Dark Matter ◽  
Observational Studies ◽  
Globular Clusters ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Large Range ◽  
Dark Matter Annihilation ◽  
Central Regions ◽  
Γ Ray ◽  
The Masses

ABSTRACT Recent observational studies of γ-ray emission from massive globular clusters (GCs) have revealed possible evidence of dark matter (DM) annihilation within GCs. It is, however, still controversial whether the emission comes from DM or from millisecond pulsars. We here present the new results of numerical simulations, which demonstrate that GCs with DM can originate from nucleated dwarfs orbiting the ancient Milky Way. The simulated stripped nuclei (i.e. GCs) have the central DM densities ranging from 0.1 to several M⊙ pc−3, depending on the orbits and the masses of the host dwarf galaxies. However, GCs born outside the central regions of their hosts can have no/little DM after their hosts are destroyed and the GCs become the Galactic halo GCs. These results suggest that only GCs originating from stellar nuclei of dwarfs can possibly have DM. We further calculate the expected γ-ray emission from these simulated GCs and compare them to observations of ω Cen. Given the large range of DM densities in the simulated GCs, we suggest that the recent possible detection of DM annihilation from GCs should be more carefully interpreted.

scholarly journals Globular clusters in high-redshift dwarf galaxies: a case study from the Local Group

2018 ◽  
Vol 477 (1) ◽  
pp. 480-490 ◽  
Author(s):  
Tom O Zick ◽  
Daniel R Weisz ◽  
Michael Boylan-Kolchin
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Dwarf Galaxies ◽  
High Redshift

scholarly journals H I IN LOCAL GROUP DWARF GALAXIES AND STRIPPING BY THE GALACTIC HALO

2009 ◽  
Vol 696 (1) ◽  
pp. 385-395 ◽  
Author(s):  
Jana Grcevich ◽  
Mary E Putman
Keyword(s):  
Local Group ◽  
Galactic Halo ◽  
Dwarf Galaxies

What are the implications of stellar chemical abundances in dwarf galaxies?

2018 ◽  
Vol 14 (S344) ◽  
pp. 220-221
Author(s):  
Takuma Suda ◽  
Wako Aoki ◽  
Yutaka Katsuta ◽  
Shimako Yamada ◽  
Tadafumi Matsuno ◽  
...  
Keyword(s):  
Local Group ◽  
Dwarf Galaxies ◽  
Chemical Abundances ◽  
Interstellar Gas ◽  
Process Elements ◽  
The Relationship

AbstractWe analyse the chemical abundances of stars in the local group dwarf galaxies using the SAGA database. The inspection of the relationship between Eu and Ba abundances confirms an anomalously Ba-rich population in Fornax, which indicates a pre-enrichment of interstellar gas with r-process elements.

scholarly journals Detailed abundance analysis of globular clusters in the Local Group

2018 ◽  
Vol 613 ◽  
pp. A56 ◽  
Author(s):  
S. S. Larsen ◽  
J. P. Brodie ◽  
A. Wasserman ◽  
J. Strader
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Element Abundances ◽  
Abundance Patterns ◽  
Lack Of Information ◽  
Very Large Telescope ◽  
Ngc 6822 ◽  
Milky Way Halo

Context. Globular clusters (GCs) are emerging as powerful tracers of the chemical composition of extragalactic stellar populations. Aims. We present new abundance measurements for 11 GCs in the Local Group galaxies NGC 147, NGC 6822, and Messier 33. These are combined with previously published observations of four GCs in the Fornax and Wolf–Lundmark–Melotte (WLM) galaxies. Methods. The abundances were determined from analyses of integrated-light spectra obtained with the HIRES spectrograph on the Keck I telescope and with UVES on the Very Large Telescope (VLT). We used our analysis technique that was developed for this purpose and tested on Milky Way GCs. Results. We find that the clusters with [Fe∕H] < −1.5 are all α-enhanced at about the same level as Milky Way GCs. Their Na abundances are also generally enhanced relative to Milky Way halo stars, suggesting that these extragalactic GCs resemble their Milky Way counterparts in containing large numbers of Na-rich stars. For [Fe∕H] > −1.5, the GCs in M33 are also α-enhanced, while the GCs that belong to dwarfs (NGC 6822 SC7 and Fornax 4) have closer to solar-scaled α-element abundances. The abundance patterns in SC7 are remarkably similar to those in the Galactic GC Ruprecht 106, including significantly subsolar [Na∕Fe] and [Ni∕Fe] ratios. In NGC 147, the GCs with [Fe∕H] < −2.0 account for about 6% of the total luminosity of stars in the same metallicity range, a lower fraction than those previously found in the Fornax and WLM galaxies, but substantially higher than in the Milky Way halo. Conclusions. At low metallicities, the abundance patterns suggest that GCs in the Milky Way, dwarf galaxies, and M33 experienced similar enrichment histories and/or processes. At higher metallicities, the lower levels of α-enhancement in the GCs found in dwarf galaxies resemble the abundance patterns observed in field stars in nearby dwarfs. Constraining the presence of multiple populations in these GCs is complicated by lack of information about detailed abundances in field stars of the corresponding metallicities. We suggest that correlations such as [Na∕Fe] versus [Ni∕Fe] may prove useful for this purpose if an accuracy of ~ 0.1 dex or better can be reached for integrated-light measurements.

scholarly journals A search for stellar tidal debris of defunct dwarf galaxies around globular clusters in the inner Galactic halo

2014 ◽  
Vol 445 (3) ◽  
pp. 2971-2993 ◽  
Author(s):  
Julio A. Carballo-Bello ◽  
Antonio Sollima ◽  
David Martínez-Delgado ◽  
Berenice Pila-Díez ◽  
Ryan Leaman ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Dwarf Galaxies

scholarly journals The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. II. The Star-formation History of Andromeda I Derived from Long-period Variables

2021 ◽  
Vol 923 (2) ◽  
pp. 164
Author(s):  
Elham Saremi ◽  
Atefeh Javadi ◽  
Mahdieh Navabi ◽  
Jacco Th. van Loon ◽  
Habib G. Khosroshahi ◽  
...  
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Star Formation History ◽  
Isaac Newton ◽  
Long Period ◽  
Formation History ◽  
Monitoring Survey ◽  
Isaac Newton Telescope

Abstract An optical monitoring survey in the nearby dwarf galaxies was carried out with the 2.5 m Isaac Newton Telescope. 55 dwarf galaxies and four isolated globular clusters in the Local Group were observed with the Wide Field Camera. The main aims of this survey are to identify the most evolved asymptotic giant branch stars and red supergiants at the endpoint of their evolution based on their pulsational instability, use their distribution over luminosity to reconstruct the star-formation history (SFH), quantify the dust production and mass loss from modeling the multiwavelength spectral energy distributions, and relate this to luminosity and radius variations. In this second of a series of papers, we present the methodology used to estimate SFH based on long-period variable (LPV) stars and then derive it for Andromeda I (And I) dwarf galaxy as an example of the survey. Using our identified 59 LPV candidates within two half-light radii of And I and Padova stellar evolution models, we estimated the SFH of this galaxy. A major epoch of star formation occurred in And I peaking around 6.6 Gyr ago, reaching 0.0035 ± 0.0016 M ⊙ yr−1 and only slowly declining until 1–2 Gyr ago. The presence of some dusty LPVs in this galaxy corresponds to a slight increase in recent star formation peaking around 800 Myr ago. We evaluate a quenching time around 4 Gyr ago (z < 0.5), which makes And I a late-quenching dSph. A total stellar mass (16 ± 7) × 106 M ⊙ is calculated within two half-light radii of And I for a constant metallicity Z = 0.0007.

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