Terzan 5: a pristine fragment of the Bulge

AbstractWe have discovered that Terzan 5, a stellar system in the Galactic Bulge, harbors two stellar populations with different iron content (Δ[Fe/H] ~ 0.5 dex) and possibly different ages. Moreover, the observed chemical patterns significantly differ from those observed in any known genuine globular cluster. These evidences demonstrate that, similarly to ω Centauri in the Halo, Terzan 5 is not a globular cluster, but a stellar system that was able to retain the gas ejected by violent supernova explosions. Moreover the striking chemical similarity with the Bulge stars suggests that Terzan 5 could be the relic of one of the massive clumps that contributed (through strong dynamical interactions with other pre-formed and internally-evolved sub-structures) to the formation of the Galactic Bulge.

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Globular cluster tidal interactions and mergers in the Galactic disc

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319007853 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 442-446

Author(s):

Alessandra Mastrobuono-Battisti ◽

Sergey Khoperskov ◽

Paola Di Matteo ◽

Misha Haywood

Keyword(s):

Globular Cluster ◽

Iron Content ◽

Globular Clusters ◽

Dynamical Evolution ◽

Stellar Populations ◽

Cluster System ◽

Galactic Disc ◽

Tidal Interactions ◽

Globular Cluster System ◽

Shed Light

AbstractThe Galactic globular cluster system went and is still going through dynamical processes that require to be explored in detail. Here we illustrate how primordial massive globular clusters born in the Milky Way’s disc evolved by stripping material from each other or even merging very early during their lives. These processes might explain the puzzling presence of star-by-star spreads in iron content observed in massive globular clusters and should be taken into account when studying globular cluster stellar populations. In this context, we show how the direct comparison between the predictions provided by our direct N-body simulations and observations can shed light on the origin and chemo-dynamical evolution of globular clusters.

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Cluster Distances using δ Sct Stars; Oscillating Blue Stragglers in ω Cen

Symposium - International Astronomical Union ◽

10.1017/s007418090022353x ◽

2002 ◽

Vol 207 ◽

pp. 138-139

Author(s):

L.M. Freyhammer ◽

Jørgen Otzen Petersen

Keyword(s):

Spatial Distribution ◽

Star Formation ◽

Globular Cluster ◽

Stellar Populations ◽

Star Formation History ◽

Blue Stragglers ◽

Formation History ◽

Oscillation Modes ◽

Different Ages ◽

History Of

The complicated star formation history of the most massive globular cluster in our Galaxy — ω Centauri — is seen as a presence of an asymmetric spatial distribution of two stellar populations having different ages and metallicities. The cluster hosts the largest known sample of Population II δ Sct variables, or SX Phœnicis stars, which are valuable Galactic and extragalactic distance estimators. We discuss the applicability of these variables for estimating distances to the cluster, and compare different techniques for the critical identifications of oscillation modes.

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On the origin of the helium-rich population in the peculiar globular cluster Omega Centauri

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310004114 ◽

2009 ◽

Vol 5 (S268) ◽

pp. 187-188

Author(s):

Donatella Romano ◽

M. Tosi ◽

M. Cignoni ◽

F. Matteucci ◽

E. Pancino ◽

...

Keyword(s):

Chemical Composition ◽

Globular Cluster ◽

Main Sequence ◽

Milky Way ◽

Dwarf Galaxy ◽

Potential Well ◽

Galactic Winds ◽

Supernova Explosions

AbstractIn this contribution we discuss the origin of the extreme helium-rich stars which inhabit the blue main sequence (bMS) of the Galactic globular cluster Omega Centauri. In a scenario where the cluster is the surviving remnant of a dwarf galaxy ingested by the Milky Way many Gyr ago, the peculiar chemical composition of the bMS stars can be naturally explained by considering the effects of strong differential galactic winds, which develop owing to multiple supernova explosions in a shallow potential well.

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Metal-poor globular clusters of the galactic bulge

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310000840 ◽

2009 ◽

Vol 5 (S265) ◽

pp. 344-345

Author(s):

B. Barbuy ◽

S. Ortolani ◽

M. Zoccali ◽

V. Hill ◽

D. Minniti ◽

...

Keyword(s):

Globular Clusters ◽

Stellar Populations ◽

Galactic Bulge ◽

Abundance Pattern ◽

Individual Stars

AbstractVery few abundance analyses of individual stars in metal-poor globular clusters in the galactic bulge are available. The main purpose of this study is to derive abundances in individual stars of such clusters, in order to establish their abundance pattern, trying to characterize the oldest bulge stellar populations.

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Extragalactic GCs in the near-infrared: genuinely old in E/S0's?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310003017 ◽

2009 ◽

Vol 5 (S262) ◽

pp. 315-316

Author(s):

Ana L. Chies-Santos ◽

Søren S. Larsen

Keyword(s):

Globular Cluster ◽

Stellar Population ◽

Near Infrared ◽

Local Group ◽

Stellar Populations ◽

Age Dating ◽

Early Type ◽

Optical Photometry ◽

Star Forming ◽

Optical Images

Globular cluster (GC) systems are powerful probes to study the evolutionary histories of galaxies, being tracers of major star fomation episodes (Brodie & Strader 2006). They are found around all major galaxies and are easy to see far beyond the local group. Age dating GCs therefore helps pinpoint epochs of major star forming events. Spectroscopic age dating though (Strader et al. 2005) is extremely time consuming and can only access the few brightest clusters. An alternative is to combine near-infrared (NIR) and optical photometry, and therefore have a better chance in lifting the age metallicity degeneracy than with optical colours alone. This approach relies in testing GC colours against simple stellar population (SSP) models. The first studies following this technique showed the possible existence of a high percentage of intermediate age (2-3 Gyrs) GCs in early-type galaxies known to contain old stellar populations from integrated light studies. Two strong cases can be listed: NGC 4365 (Puzia et al. 2002, Larsen et al. 2005) and NGC 5846 (Hempel et al. 2003). In the present study we combine NIR deep photometry obtained with the WHT/LIRIS instrument and archival HST/ACS optical images to determine g(F475W), z(F840LP) and K(2.2m) magnitudes and colours of GCs in 14 early-type galaxies.

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