Chemical Abundances for Seven Giant Stars in M68 (NGC 4590): A Globular Cluster with Abnormal Silicon and Titanium Abundances

2005 ◽  
Vol 129 (1) ◽  
pp. 251-266 ◽  
Author(s):  
Jae-Woo Lee ◽  
Bruce W. Carney ◽  
Michael J. Habgood
Keyword(s):  
Globular Cluster ◽  
Chemical Abundances ◽  
Giant Stars

scholarly journals Chemical Abundances in Giant Stars of the Tidally Disrupted Globular Cluster NGC 6712 from High‐Resolution Infrared Spectroscopy

2008 ◽  
Vol 689 (2) ◽  
pp. 1020-1030 ◽  
Author(s):  
David Yong ◽  
Jorge Meléndez ◽  
Katia Cunha ◽  
Amanda I. Karakas ◽  
John E. Norris ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
High Resolution ◽  
Globular Cluster ◽  
Chemical Abundances ◽  
Giant Stars

scholarly journals Chemical Abundances of Red Giant Stars in the Globular Cluster M107 (NGC 6171)

2011 ◽  
Vol 123 (908) ◽  
pp. 1139-1148 ◽  
Author(s):  
Julia E. O’Connell ◽  
Christian I. Johnson ◽  
Catherine A. Pilachowski ◽  
Geoffrey Burks
Keyword(s):  
Globular Cluster ◽  
Chemical Abundances ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

scholarly journals Chemodynamics of newly identified giants with a globular cluster like abundance patterns in the bulge, disc, and halo of the Milky Way

2019 ◽  
Vol 488 (2) ◽  
pp. 2864-2880 ◽  
Author(s):  
José G Fernández-Trincado ◽  
Timothy C Beers ◽  
Baitian Tang ◽  
Edmundo Moreno ◽  
Angeles Pérez-Villegas ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
First Generation ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Main Element ◽  
Chemical Abundances ◽  
Giant Stars ◽  
Halo Population ◽  
Process Elements

ABSTRACT The latest edition of the APOGEE-2/DR14 survey catalogue and the first Payne data release of APOGEE abundance determinations by Ting et al. are examined. We identify 31 previously unremarked metal-poor giant stars with anomalously high levels of [N/Fe] abundances, which is not usually observed among metal-poor stars in the Milky Way. We made use of the Brussels Automatic Stellar Parameter (BACCHUS) code to re-derive manually the chemical abundances of 31 field stars in order to compile the main element families, namely the light elements (C, N), a-elements (O, Mg, Si), iron-peak element (Fe), s-process elements (Ce, Nd), and the light odd-Z element (Na, Al). We have found all these objects have a [N/Fe] ≳ +0.5, and are thus identified here as nitrogen-rich stars. An orbital analysis of these objects revealed that a handful of them shares the orbital properties of the bar/bulge, and possibly linked to tidal debris of surviving globular clusters trapped into the bar component. Three of the 31 stars are actually halo interlopers into the bulge area, which suggests that halo contamination is not insignificant when studying N-rich stars found in the inner Galaxy, whereas the rest of the N-rich stars share orbital properties with the halo population. Most of the newly identified population exhibits chemistry similar to the so-called second-generation globular cluster stars (enriched in aluminum, [Al/Fe] ≳ +0.5), whereas a handful of them exhibit lower abundances of aluminum, [Al/Fe] < +0.5, which are thought to be chemically associated with the first generation of stars, as seen in globular clusters, or compatible with origin from a tidally disrupted dwarf galaxy.

scholarly journals Chemical abundances in tidally disrupted globular clusters

2009 ◽  
Vol 5 (S266) ◽  
pp. 157-160
Author(s):  
D. Yong ◽  
J. Meléndez ◽  
K. Cunha ◽  
A. I. Karakas ◽  
J. E. Norris ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Preliminary Analysis ◽  
Globular Clusters ◽  
Building Blocks ◽  
Light Elements ◽  
Chemical Abundances ◽  
Chemical Enrichment ◽  
Abundance Variation

AbstractWe present abundance measurements in the tidally disrupted globular cluster NGC 6712. In this cluster, there are large star-to-star variations of the light elements C, N, O, F and Na. While such abundance variations are seen in every well-studied globular cluster, they are not found in field stars and indicate that clusters like NGC 6712 cannot provide many field stars and/or field stars do not form in environments with chemical-enrichment histories like those of NGC 6712. Preliminary analysis of NGC 5466, another tidally disrupted cluster, suggests little (if any) abundance variation for O and Na and the abundance ratios [X/Fe] are comparable to field stars at the same metallicity. Therefore, globular clusters like NGC 5466 may have been Galactic building blocks.

scholarly journals Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. II. Atomic Diffusion in M67 Stars

2019 ◽  
Vol 874 (1) ◽  
pp. 97 ◽  
Author(s):  
Diogo Souto ◽  
C. Allende Prieto ◽  
Katia Cunha ◽  
Marc Pinsonneault ◽  
Verne V. Smith ◽  
...  
Keyword(s):  
Main Sequence ◽  
Atomic Diffusion ◽  
Chemical Abundances ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

scholarly journals H-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia

2019 ◽  
Vol 627 ◽  
pp. A178 ◽  
Author(s):  
J. G. Fernández-Trincado ◽  
O. Zamora ◽  
Diogo Souto ◽  
R. E. Cohen ◽  
F. Dell’Agli ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Second Generation ◽  
Elemental Abundance ◽  
Agb Stars ◽  
Giant Stars ◽  
Abundance Patterns ◽  
Evolution Experiment ◽  
Band Spectra ◽  
Stellar Sources ◽  
Process Element

We present an elemental abundance analysis of high-resolution spectra for five giant stars spatially located within the innermost regions of the bulge globular cluster NGC 6522 and derive Fe, Mg, Al, C, N, O, Si, and Ce abundances based on H-band spectra taken with the multi-object APOGEE-north spectrograph from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Of the five cluster candidates, two previously unremarked stars are confirmed to have second-generation (SG) abundance patterns, with the basic pattern of depletion in C and Mg simultaneous with enrichment in N and Al as seen in other SG globular cluster populations at similar metallicity. In agreement with the most recent optical studies, the NGC 6522 stars analyzed exhibit (when available) only mild overabundances of the s-process element Ce, contradicting the idea that NGC 6522 stars are formed from gas enriched by spinstars and indicating that other stellar sources such as massive AGB stars could be the primary polluters of intra-cluster medium. The peculiar abundance signatures of SG stars have been observed in our data, confirming the presence of multiple generations of stars in NGC 6522.

scholarly journals OCCASO – III. Iron peak and α elements of 18 open clusters. Comparison with chemical evolution models and field stars

2019 ◽  
Vol 490 (2) ◽  
pp. 1821-1842 ◽  
Author(s):  
L Casamiquela ◽  
S Blanco-Cuaresma ◽  
R Carrera ◽  
L Balaguer-Núñez ◽  
C Jordi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Nucleosynthesis ◽  
Solar Abundances ◽  
Red Giant

ABSTRACT The study of open-cluster chemical abundances provides insights on stellar nucleosynthesis processes and on Galactic chemo-dynamical evolution. In this paper we present an extended abundance analysis of 10 species (Fe, Ni, Cr, V, Sc, Si, Ca, Ti, Mg, O) for red giant stars in 18 OCCASO clusters. This represents a homogeneous sample regarding the instrument features, method, line list and solar abundances from confirmed member stars. We perform an extensive comparison with previous results in the literature, and in particular with the Gaia FGK Benchmark stars Arcturus and $\mu$-Leo. We investigate the dependence of [X/Fe] with metallicity, Galactocentric radius (6.5 kpc < RGC < 11 kpc), age (0.3 Gyr < Age < 10 Gyr), and height above the plane (|z| < 1000 pc). We discuss the observational results in the chemo-dynamical framework, and the radial migration impact when comparing with chemical evolution models. We also use APOGEE DR14 data to investigate the differences between the abundance trends in RGC and |z| obtained for clusters and for field stars.

The determination of carbon and oxygen abundances in very metal-poor globular cluster giant stars

1992 ◽  
Vol 104 ◽  
pp. 1127 ◽  
Author(s):  
R. A. Bell ◽  
M. M. Briley ◽  
John E. Norris
Keyword(s):  
Globular Cluster ◽  
Giant Stars

Carbon and nitrogen abundances in giant stars of the metal-poor globular cluster M92

1982 ◽  
Vol 49 ◽  
pp. 207 ◽  
Author(s):  
D. F. Carbon ◽  
W. Romanishin ◽  
G. E. Langer ◽  
D. Butler ◽  
E. Kemper ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Carbon And Nitrogen ◽  
Giant Stars

scholarly journals Variations of the mixing character of dipolar mixed modes in red giant stars

2020 ◽  
Vol 495 (1) ◽  
pp. 621-636 ◽  
Author(s):  
C Jiang ◽  
M Cunha ◽  
J Christensen-Dalsgaard ◽  
QS Zhang
Keyword(s):  
Asymptotic Expansion ◽  
Stellar Evolution ◽  
Coupling Strength ◽  
Stellar Model ◽  
Quality Data ◽  
Chemical Abundances ◽  
Giant Stars ◽  
Mixing Character ◽  
Mixed Modes ◽  
Red Giant

ABSTRACT Because of the high-quality data of space missions, the detection of mixed modes has become possible in numerous stars. In this work, we investigate how the mixing character of dipolar mixed modes changes with stellar evolution, as well as with frequency within each stellar model. This is achieved by monitoring the variations in the coupling strength and the period spacing of dipolar mixed modes in red-giant models. These parameters are measured by fitting the asymptotic expansion of mixed modes to the model frequencies of a grid of red-giant models with masses between 1.0 and 2.0 M⊙ and three different chemical abundances. The coupling strength and the period spacing decrease with stellar evolution. We find that the slopes of their decreasing trends depend on the radial order of the pressure mode component. A non-negligible increase of the coupling strength with frequency by up to around 40 per cent is found in the observable frequency range for a set of red-giant models. On the contrary, no significant changes of the period spacing with frequency are found. The changes in the mixing character of the modes are in most cases affected by the model mass and metallicity. Buoyancy glitches also have an impact on the mixing character. Significant fluctuations in the estimated coupling strength and period spacing are found for models approaching the luminosity bump, if the glitch impact of the frequencies is not considered in the applied asymptotic expansion.

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