scholarly journals Heart of darkness: dust obscuration of the central stellar component in globular clusters younger than ∼100 Myr in multiple stellar population models

2015 ◽  
Vol 448 (1) ◽  
pp. L62-L66 ◽  
Author(s):  
S. N. Longmore
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Population Models ◽  
Stellar Component ◽  
Heart Of Darkness

scholarly journals The WAGGS project-III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity

2020 ◽  
Vol 492 (3) ◽  
pp. 3859-3871 ◽  
Author(s):  
H Dalgleish ◽  
S Kamann ◽  
C Usher ◽  
H Baumgardt ◽  
N Bastian ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Milky Way ◽  
Population Models ◽  
Theoretical Predictions ◽  
Field Unit ◽  
Stellar Masses ◽  
Kinematic Information ◽  
High Metallicity ◽  
Integral Field

ABSTRACT Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1622 stars located in the centres of 59 Milky Way GCs – 12 of which have no previous kinematic information – using integral-field unit data from the WAGGS project. Using N-body models, we determine dynamical masses and M/LV for the studied clusters. Our sample includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/L up to [Fe/H] ∼ −0.1 dex. We find that metal-rich clusters have M/LV more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L–[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the divergence, which we conclude is most likely due to dynamical effects.

scholarly journals IntegratedJ- andH-band spectra of globular clusters in the LMC: implications for stellar population models and galaxy age dating

2012 ◽  
Vol 543 ◽  
pp. A75 ◽  
Author(s):  
M. Lyubenova ◽  
H. Kuntschner ◽  
M. Rejkuba ◽  
D. R. Silva ◽  
M. Kissler-Patig ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Population Models ◽  
Age Dating ◽  
Band Spectra

scholarly journals Stellar population models based on the SDSS-IV MaStar library of stellar spectra – I. Intermediate-age/old models

2020 ◽  
Vol 496 (3) ◽  
pp. 2962-2997 ◽  
Author(s):  
C Maraston ◽  
L Hill ◽  
D Thomas ◽  
R Yan ◽  
Y Chen ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Globular Clusters ◽  
Stellar Population ◽  
Population Models ◽  
Full Account ◽  
Stellar Spectra ◽  
Novel Approach ◽  
Calibration Sets ◽  
Low Metallicity ◽  
Cold Metal

ABSTRACT We use the first release of the SDSS/MaStar stellar library comprising ∼9000, high S/N spectra, to calculate integrated spectra of stellar population models. The models extend over the wavelength range 0.36–1.03 µm and share the same spectral resolution ($R\sim 1800$) and flux calibration as the SDSS-IV/MaNGA galaxy data. The parameter space covered by the stellar spectra collected thus far allows the calculation of models with ages and chemical composition in the range $\rm {\mathit{ t}\gt 200 \,Myr, -2 \lt = [Z/H] \lt = + 0.35}$, which will be extended as MaStar proceeds. Notably, the models include spectra for dwarf main-sequence stars close to the core H-burning limit, as well as spectra for cold, metal-rich giants. Both stellar types are crucial for modelling λ > 0.7 µm absorption spectra. Moreover, a better parameter coverage at low metallicity allows the calculation of models as young as 500 Myr and the full account of the blue horizontal branch phase of old populations. We present models adopting two independent sets of stellar parameters (Teff, log g, [Z/H]). In a novel approach, their reliability is tested ‘on the fly’ using the stellar population models themselves. We perform tests with Milky Way and Magellanic Clouds globular clusters, finding that the new models recover their ages and metallicities remarkably well, with systematics as low as a few per cent for homogeneous calibration sets. We also fit a MaNGA galaxy spectrum, finding residuals of the order of a few per cent comparable to the state-of-art models, but now over a wider wavelength range.

scholarly journals Ultra-Compact Dwarf Galaxies – More Massive than Allowed?

2007 ◽  
Vol 3 (S246) ◽  
pp. 427-428 ◽  
Author(s):  
Michael Hilker ◽  
S. Mieske ◽  
H. Baumgardt ◽  
J. Dabringhausen
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Dwarf Galaxies ◽  
Population Models ◽  
High Mass ◽  
Early Type ◽  
Dynamical Mass ◽  
Dispersion Diagram

AbstractDynamical mass estimates of ultra-compact dwarfs galaxies and massive globular clusters in the Fornax and Virgo clusters and around the giant elliptical Cen A have revealed some surprising results: 1) above ~106M⊙ the mass-to-light (M/L) ratio increases with the objects' mass; 2) some UCDs/massive GCs show high M/L values (4 to 6) that are not compatible with standard stellar population models; and 3) in the luminosity-velocity dispersion diagram, UCDs deviate from the well-defined relation of “normal” GCs, being more in line with the Faber-Jackson relation of early-type galaxies. In this contribution, we present the observational evidences for high mass-to-light ratios of UCDs and discuss possible explanations for them.

scholarly journals Matching Stellar Population Models to Bulge Globular Clusters.

1997 ◽  
Vol 114 ◽  
pp. 1531 ◽  
Author(s):  
G. Bruzual ◽  
B. Barbuy ◽  
S. Ortolani ◽  
E. Bica ◽  
F. Cuisinier ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Population Models

scholarly journals GALEX Ultraviolet Observations of Globular Clusters in Nearby Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 332-332
Author(s):  
Soo-Chang Rey ◽  
Sangmo T. Sohn ◽  
R. Michael Rich ◽  
Suk-Jin Yoon ◽  
Chul Chung ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Globular Clusters ◽  
Stellar Population ◽  
Population Models ◽  
Horizontal Branch ◽  
Uv Photometry ◽  
Nearby Galaxies ◽  
Ultraviolet Observations

The hot He-burning horizontal-branch (HB) stars and their progeny are most likely dominant ultraviolet (UV) sources in the old stellar population systems such as globular clusters (GCs). Integrated FUV flux can be an age indicator of GCs and allow us to investigate age distributions of GCs within a given galaxy or between galaxies. The unprecedented set of UV photometry for M31 by Galaxy Evolution Explorer (GALEX), coupled with most recent detailed population models enable to study detailed global UV properties of M31 GCs.

scholarly journals Near-infrared integrated spectra of Galactic globular clusters: testing simple stellar population models

2010 ◽  
Vol 410 (4) ◽  
pp. 2714-2724 ◽  
Author(s):  
R. Riffel ◽  
D. Ruschel-Dutra ◽  
M. G. Pastoriza ◽  
A. Rodríguez-Ardila ◽  
J. F. C. Santos Jr ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Near Infrared ◽  
Population Models ◽  
Galactic Globular Clusters
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