scholarly journals New insights into the star formation histories of candidate intermediate-age early-type galaxies from K′-band imaging of globular clusters

2012 ◽  
Vol 420 (2) ◽  
pp. 1317-1332 ◽  
Author(s):  
Iskren Y. Georgiev ◽  
Paul Goudfrooij ◽  
Thomas H. Puzia
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Early Type ◽  
Star Formation Histories ◽  
K Band

scholarly journals Evolution of the Ultraviolet Upturn at 0.3 < z < 1: Exploring Helium-rich Stellar Populations

2021 ◽  
Vol 923 (1) ◽  
pp. 12
Author(s):  
Sadman S. Ali ◽  
Roberto De Propris ◽  
Chul Chung ◽  
Steven Phillipps ◽  
Malcolm N. Bremer
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Rest Frame ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Early Type ◽  
Similar Chemical ◽  
Far Ultraviolet ◽  
Star Formation Histories ◽  
Optical Color

Abstract We measure the near-UV (rest-frame ∼2400 Å) to optical color for early-type galaxies in 12 clusters at 0.3 < z < 1.0. We show that this is a suitable proxy for the more common far-ultraviolet bandpass used to measure the ultraviolet upturn and find that the upturn is detected to z = 0.6 in these data, in agreement with previous work. We find evidence that the strength of the upturn starts to wane beyond this redshift and largely disappears at z = 1. Our data are most consistent with models where early-type galaxies contain minority stellar populations with non-cosmological helium abundances, up to around 46%, formed at z ≥ 3, resembling globular clusters with multiple stellar populations in our Galaxy. This suggests that elliptical galaxies and globular clusters share similar chemical evolution and star formation histories. The vast majority of the stellar mass in these galaxies also must have been in place at z > 3.

scholarly journals Star formation histories of resolved galaxies

2008 ◽  
Vol 4 (S258) ◽  
pp. 61-72
Author(s):  
Monica Tosi
Keyword(s):  
Star Formation ◽  
Observational Data ◽  
Stellar Populations ◽  
Morphological Type ◽  
The Other ◽  
Early Type ◽  
Significant Rate ◽  
Star Formation Histories

AbstractThe colour-magnitude diagrams of resolved stellar populations are the best tool to study the star formation histories of the host galactic regions. In this review the method to derive star formation histories by means of synthetic colour-magnitude diagrams is briefly outlined, and the results of its application to resolved galaxies of various morphological types are summarized. It is shown that all the galaxies studied so far were already forming stars at the lookback time reached by the observational data, independently of morphological type and metallicity. Early-type galaxies have formed stars predominantly, but in several cases not exclusively, at the earliest epochs. All the other galaxies appear to have experienced rather continuous star formation activities throughout their lifetimes, although with significant rate variations and, sometimes, short quiescent phases.

scholarly journals A TALE OF A RICH CLUSTER ATz∼ 0.8 AS SEEN BY THE STAR FORMATION HISTORIES OF ITS EARLY-TYPE GALAXIES

2014 ◽  
Vol 797 (2) ◽  
pp. 136 ◽  
Author(s):  
Anna Ferré-Mateu ◽  
Patricia Sánchez-Blázquez ◽  
Alexandre Vazdekis ◽  
Ignacio G. de la Rosa
Keyword(s):  
Star Formation ◽  
Early Type ◽  
Rich Cluster ◽  
Star Formation Histories

scholarly journals CHEMICAL ABUNDANCE EVIDENCE OF ENDURING HIGH STAR FORMATION RATES IN AN EARLY-TYPE GALAXY: HIGH [Ca/Fe] IN NGC 5128 GLOBULAR CLUSTERS

2013 ◽  
Vol 773 (2) ◽  
pp. L36 ◽  
Author(s):  
Janet E. Colucci ◽  
María Fernanda Durán ◽  
Rebecca A. Bernstein ◽  
Andrew McWilliam
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Early Type ◽  
Chemical Abundance ◽  
Early Type Galaxy

scholarly journals Observational Comparison of Star Formation in Different Galaxy Types

2010 ◽  
Vol 6 (S270) ◽  
pp. 335-346
Author(s):  
Eva K. Grebel
Keyword(s):  
Star Formation ◽  
Variable Star ◽  
High Mass ◽  
Early Type ◽  
Intermediate Mass ◽  
Wide Range ◽  
Low Mass ◽  
Key Features ◽  
Star Formation Histories ◽  
Hubble Time

AbstractGalaxies cover a wide range of masses and star formation histories. In this review, I summarize some of the evolutionary key features of common galaxy types. At the high-mass end, very rapid, efficient early star formation is observed, accompanied by strong enrichment and later quiescence, well-described by downsizing scenarios. In the intermediate-mass regime, early-type galaxies may still show activity in low-mass environments or when being rejuvenated by wet mergers. In late-type galaxies, we find continuous, though variable star formation over a Hubble time. In the dwarf regime, a wide range of properties from bursty activity to quiescence is observed. Generally, stochasticity dominates here, and star formation rates and efficiencies tend to be low. Morphological types and their star formation properties correlate with environment.

scholarly journals Star Formation Histories of Dwarf Galaxies from the Colour-Magnitude Diagrams of Their Resolved Stellar Populations

2010 ◽  
Vol 2010 ◽  
pp. 1-25 ◽  
Author(s):  
Michele Cignoni ◽  
Monica Tosi
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
Early Type ◽  
Significant Difference ◽  
Magnitude Diagram ◽  
The Galaxy ◽  
Show Evidence ◽  
History Of ◽  
Star Formation Histories

In this tutorial paper we summarize how the star formation (SF) history of a galactic region can be derived from the colour-magnitude diagram (CMD) of its resolved stars. The procedures to build synthetic CMDs and to exploit them to derive the SF histories (SFHs) are described, as well as the corresponding uncertainties. The SFHs of resolved dwarf galaxies of all morphological types, obtained from the application of the synthetic CMD method, are reviewed and discussed. To summarize: (1) only early-type galaxies show evidence of long interruptions in the SF activity; late-type dwarfs present rather continuous, orgasping, SF regimes; (2) a few early-type dwarfs have experienced only one episode of SF activity concentrated at the earliest epochs, whilst many others show extended or recurrent SF activity; (3) no galaxy experiencing now its first SF episode has been found yet; (4) no frequent evidence of strong SF bursts is found; (5) there is no significant difference in the SFH of dwarf irregulars and blue compact dwarfs, except for the current SF rates. Implications of these results on the galaxy formation scenarios are briefly discussed.

scholarly journals Results from HST Observations of Six LMC Globular Cluster Fields

1999 ◽  
Vol 190 ◽  
pp. 448-449 ◽  
Author(s):  
K. A. G. Olsen ◽  
P. W. Hodge ◽  
M. Mateo ◽  
E. W. Olszewski ◽  
R. A. Schommer ◽  
...  
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Milky Way ◽  
Evolutionary Models ◽  
First Stars ◽  
Field Star ◽  
Star Studies ◽  
Red Giant ◽  
Star Formation Histories ◽  
Best Fit

We present deep HST color-magnitude diagrams of fields centered on the six old LMC globular clusters NGC 1754, NGC 1835, NGC 1898, NGC 1916, NGC 2005, and NGC 2019. Separate cluster and field star CMDs are shown. The time of formation of the LMC is studied from an analysis of the cluster CMDs. Based on a comparison of the CMDs with sequences of the Milky Way clusters M3, M5, and M55, we suggest that the LMC formed its first stars at the same time as the Milky Way to within 1 Gyr. We find additional evidence that these LMC globular clusters are as old as the oldest Milky Way clusters through a comparison of our data with the horizontal branch evolutionary models of Lee, Demarque, & Zinn (1994).The evolution of the LMC following its formation is studied through an analysis of the field star CMDs. Through an automated comparison with stellar evolution models, we extract the star formation histories implied by the CMDs. Our best-fit star formation histories imply that the LMC has been actively forming stars over the last 4 Gyr, in agreement with previous field star studies. The four fields that lie in the Bar also contain significant numbers of stars with ages of 4–8 Gyr in the best-fit cases. The most notable disagreement between the best-fit models and observed CMDs is in the color of the red giant branch.

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