The Bolometric Corrections and Effective Temperatures of Two Giant Stars in the Globular Cluster M3

1966 ◽  
Vol 146 ◽  
pp. 613 ◽  
Author(s):  
H. L. Johnson
Keyword(s):  
Globular Cluster ◽  
Giant Stars ◽  
Effective Temperatures

scholarly journals Main-sequence and sub-giant stars in the globular cluster NGC 6397: The complex evolution of the lithium abundance

2009 ◽  
Vol 5 (S268) ◽  
pp. 257-261
Author(s):  
J. I. González Hernández ◽  
P. Bonifacio ◽  
E. Caffau ◽  
M. Steffen ◽  
H.-G. Ludwig ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
3D Models ◽  
Stellar Atmospheres ◽  
Evolutionary Status ◽  
Thermodynamical Equilibrium ◽  
Lithium Abundance ◽  
Giant Stars ◽  
Effective Temperatures ◽  
Hydrodynamical Simulations

AbstractThanks to the high multiplex and efficiency of Giraffe at the VLT we have been able for the first time to observe the Li I doublet in the Main Sequence stars of a globular cluster. At the same time we observed Li in a sample of Sub-Giant stars of the same B-V colour.Our final sample is composed of 84 SG stars and 79 MS stars. In spite of the fact that SG and MS span the same temperature range we find that the equivalent widths of the Li I doublet in SG stars are systematically larger than those in MS stars, suggesting a higher Li content among SG stars. This is confirmed by our quantitative analysis carried out making use of 1D hydrostatic plane-parallel models and 3D hydrodynamical simulations of the stellar atmospheres.We derived the effective temperatures of stars in our the sample from Hα fitting. Theoretical profiles were computed using 3D hydrodynamical simulations and 1D ATLAS models. Therefore, we are able to determined 1D and 3D-based effective temperatures. We then infer Li abundances taking into account non-local thermodynamical equilibrium effects when using both 1D and 3D models.We find that SG stars have a mean Li abundance higher by 0.1 dex than MS stars. This result is obtained using both 1D and 3D models. We also detect a positive slope of Li abundance with effective temperature, the higher the temperature the higher the Li abundance, both for SG and MS stars, although the slope is slightly steeper for MS stars. These results provide an unambiguous evidence that the Li abundance changes with evolutionary status.The physical mechanisms responsible for this behaviour are not yet clear, and none of the existing models seems to describe accurately these observations. Based on these conclusions, we believe that the cosmological lithium problem still remains an open question.

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.

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

Proton‐Capture Nucleosynthesis in Globular Cluster Red Giant Stars

1998 ◽  
Vol 492 (2) ◽  
pp. 575-595 ◽  
Author(s):  
Robert M. Cavallo ◽  
Allen V. Sweigart ◽  
Roger A. Bell
Keyword(s):  
Globular Cluster ◽  
Proton Capture ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

scholarly journals A Comparison of Copper Abundances in Globular Cluster and Halo Field Giant Stars

2003 ◽  
Vol 125 (4) ◽  
pp. 2018-2028 ◽  
Author(s):  
Jennifer Simmerer ◽  
Christopher Sneden ◽  
Inese I. Ivans ◽  
Robert P. Kraft ◽  
Matthew D. Shetrone ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Giant Stars

scholarly journals IUE observations of stars in NGC 330 in the Small Magellanic Cloud

1991 ◽  
Vol 148 ◽  
pp. 339-340
Author(s):  
V. Caloi ◽  
A. Cassatella ◽  
V. Castellani ◽  
G. Klare
Keyword(s):  
Globular Cluster ◽  
Massive Star ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Low Resolution ◽  
Star Evolution ◽  
Theoretical Predictions ◽  
Effective Temperatures ◽  
Massive Star Evolution ◽  
Hr Diagram

Low resolution spectra from 1200 to 3300Å have been obtained, with the IUE satellite, for seven blue giants and supergiants in the young, metal-poor globular cluster NGC 330 in the Small Magellanic Cloud (SMC). A further three spectra from the IUE archive have been added to the sample, covering a range of 2.5 mag. The effective temperatures and the local reddening in the SMC have been estimated, and the star positions in the theoretical HR diagram determined, and compared with theoretical predictions for massive star evolution. Substantial discrepancies have been found.

scholarly journals Mg isotopic ratios in giant stars of the globular cluster NGC 6752

2003 ◽  
Vol 402 (3) ◽  
pp. 985-1001 ◽  
Author(s):  
D. Yong ◽  
F. Grundahl ◽  
D. L. Lambert ◽  
P. E. Nissen ◽  
M. D. Shetrone
Keyword(s):  
Globular Cluster ◽  
Isotopic Ratios ◽  
Giant Stars

scholarly journals Stellar Winds and Coronae in Cool Stars

1980 ◽  
Vol 51 ◽  
pp. 279-291 ◽  
Author(s):  
A.K. Dupree ◽  
L. Hartmann
Keyword(s):  
Theoretical Models ◽  
Stellar Winds ◽  
Late Type ◽  
Dwarf Stars ◽  
Giant Stars ◽  
Cool Stars ◽  
Thermally Driven ◽  
Effective Temperatures ◽  
Hot Corona ◽  
Theoretical Results

AbstractRecent observational and theoretical results are reviewed that pertain to the presence and characteristics of stellar coronae and winds in late-type stars. It is found that stars - principally dwarfs - exist with “hot” coronae similar to the Sun with thermally driven winds. For stars, at the lowest effective temperatures, and gravities characteristic of supergiant and giant stars, high temperature (~105K) atmospheres are absent (or if present are substantially weaker than in the dwarf stars), and massive winds are present. There also exist “hybrid” examples - luminous stars possessing both a “hot” corona and a supersonic stellar wind. Constraints for theoretical models are discussed.

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