scholarly journals GMOS Spectroscopy of Globular Clusters in Dwarf Elliptical Galaxies

2007 ◽  
Vol 3 (S246) ◽  
pp. 429-430
Author(s):  
Bryan W. Miller ◽  
Jennifer Lotz ◽  
Michael Hilker ◽  
Markus Kissler-Patig ◽  
Thomas Puzia
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Elliptical Galaxies ◽  
Preliminary Results ◽  
Dwarf Elliptical Galaxies ◽  
Milky Way Halo

AbstractWe present a Gemini/GMOS program to measure spectroscopic metallicities and ages of globular clusters (GCs) and nuclei in dwarf elliptical galaxies in the Virgo and Fornax Clusters. Preliminary results indicate that the globular clusters are old and metal-poor, very similar to the GCs in the Milky Way halo. The nuclei tend to be more metal-rich than the globular clusters but more metal-poor and older, on average, than the stars in the bodies of the galaxies. The [α/Fe] ratio appears to be solar for the GCs, nuclei, and dEs, but the uncertainties do not exclude some globular clusters from being enhanced in alpha elements.

scholarly journals Globular Clusters in Dwarf Elliptical Galaxies

2002 ◽  
Vol 207 ◽  
pp. 303-305
Author(s):  
Bryan W. Miller ◽  
Jennifer M. Lotz ◽  
Henry C. Ferguson ◽  
Massimo Stiavelli ◽  
Bradley C. Whitmore
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Luminosity Function ◽  
Elliptical Galaxies ◽  
Preliminary Results ◽  
The Galaxy ◽  
Dwarf Elliptical Galaxies

We present preliminary results on the shape of the globular cluster luminosity function and the colors and inferred metallicities of the clusters in dwarf elliptical galaxies imaged with HST. The luminosity function (LF) of the GC candidates is consistent with a Gaussian-shaped LF similar to that in giant ellipticals. Also, with a mean color of (V - I) = 0.94, most of the GCs appear to be old and metal-poor ([Fe/H] = −1.4) like GCs in the Galaxy and in nearby giant ellipticals. This suggests that the bulk of the clusters were formed more than 10 Gyr ago.

scholarly journals The Dynamical Mass of the Young Cluster W3 in NGC 7252: Heavy-Weight Globular Cluster or Ultra-Compact Dwarf Galaxy?

2005 ◽  
Vol 13 ◽  
pp. 169-170
Author(s):  
Claudia Maraston ◽  
N. Bastian ◽  
R. P. Saglia ◽  
Markus Kissler-Patig ◽  
François Schweizer ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Elliptical Galaxies ◽  
Star Cluster ◽  
Dynamical Mass ◽  
Fundamental Plane ◽  
Dwarf Elliptical Galaxies ◽  
First Time

AbstractWe have measured the dynamical mass of the highly luminous star cluster W3 in the young merger remnant galaxy NGC 7252. The value is Mdyn = (8 ± 2) × 107M⊙, and represents the highest dynamically-confirmed mass for an extra-galactic star cluster so far. The dynamical mass is in excellent agreement with the luminous mass (Maraston et al. 2001). This results from the use of stellar population models that include correctly the brightest AGB stellar phase, dominant in young stellar populations. To classify W3, we employ the fundamental plane of stellar systems (Bender, Burstein & Faber 1992), for the first time in these kinds of studies. We find that W3 lies far from typical Milky Way globular clusters, but it is also far from the heavyweights ωCen in the Milky Way and G1 in M31, because it is too extended for its mass, and from dwarf elliptical galaxies because it is much more compact for its mass. Instead W3 lies close to the ultra-compact Fornax objects (Drinkwater et al. 2003) and to the compact elliptical M32, possibly shedding light on the still mysterious nature of these objects. A previously deserted region of the fundamental plane starts to be populated.

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 Tidal Effects on Spherical Stellar Systems

1975 ◽  
Vol 69 ◽  
pp. 53-55
Author(s):  
D. W. Keenan ◽  
K. A. Innanen
Keyword(s):  
Internal Structure ◽  
Globular Clusters ◽  
Elliptical Galaxies ◽  
Star Cluster ◽  
Stellar Systems ◽  
Tidal Effects ◽  
Dwarf Elliptical Galaxies

Many self-gravitating stellar systems are satellites of larger galaxies and must therefore be subjected to the tidal field of the parent system. Examples are the globular clusters and dwarf elliptical galaxies, which are satellites of our Galaxy. Most previous studies of tidal effects have been highly simplified, e.g. clusters in circular planar galactic orbits (Bok, 1934), or have assumed that the tidal field acts to limit the size of a star cluster without any effects on its internal structure or stability (Spitzer and Shapiro, 1972; Spitzer and Thuan, 1972).

scholarly journals Modeling mass independent of anisotropy

2010 ◽  
Vol 6 (S271) ◽  
pp. 110-118
Author(s):  
Joe Wolf
Keyword(s):  
Spatial Variation ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Galaxy Cluster ◽  
Elliptical Galaxies ◽  
Line Of Sight ◽  
Dwarf Spheroidal Galaxies ◽  
Dispersion Profile ◽  
Stellar Velocity ◽  
Dwarf Elliptical Galaxies

AbstractBy manipulating the spherical Jeans equation, Wolf et al. (2010) show that the mass enclosed within the 3D deprojected half-light radius r1/2 can be determined with only mild assumptions about the spatial variation of the stellar velocity dispersion anisotropy as long as the projected velocity dispersion profile is fairly flat near the half-light radius, as is typically observed. They find M1/2 = 3 G−1 〈σ2los〉 r1/2 ≃ 4 G−1 〈σ2los〉 Re, where 〈σ2los〉 is the luminosity-weighted square of the line-of-sight velocity dispersion and Re is the 2D projected half-light radius. This finding can be used to show that all of the Milky Way dwarf spheroidal galaxies (MW dSphs) are consistent with having formed within a halo of mass approximately 3 × 109 M⊙, assuming a ΛCDM cosmology. In addition, the dynamical I-band mass-to-light ratio ϒI1/2 vs. M1/2 relation for dispersion-supported galaxies follows a U-shape, with a broad minimum near ϒI1/2 ≃ 3 that spans dwarf elliptical galaxies to normal ellipticals, a steep rise to ϒI1/2 ≃ 3,200 for ultra-faint dSphs, and a more shallow rise to ϒI1/2 ≃ 800 for galaxy cluster spheroids.

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 The building blocks of the Milky Way halo using APOGEE and Gaia or Is the Galaxy a typical galaxy?

2019 ◽  
Vol 14 (S351) ◽  
pp. 170-173 ◽  
Author(s):  
Ricardo P. Schiavon ◽  
J. Ted Mackereth ◽  
Joel Pfeffer ◽  
Rob A. Crain ◽  
Jo Bovy
Keyword(s):  
Numerical Simulations ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Stellar Populations ◽  
Building Blocks ◽  
Stellar Content ◽  
The Galaxy ◽  
Milky Way Halo

AbstractWe summarise recent results from analysis of APOGEE/Gaia data for stellar populations in the Galactic halo, disk, and bulge, leading to constraints on the contribution of dwarf galaxies and globular clusters to the stellar content of the Milky Way halo. Intepretation of the extant data in light of cosmological numerical simulations suggests that the Milky Way has been subject to an unusually intense accretion history at z ≳ 1.5.

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