On the number ratio of horizontal branch stars to red giant stars in globular clusters

1981 ◽  
Vol 76 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Nobuo Arimoto ◽  
Mahiro Simoda
Keyword(s):  
Globular Clusters ◽  
Horizontal Branch ◽  
Giant Stars ◽  
Number Ratio ◽  
Horizontal Branch Stars ◽  
Red Giant Stars ◽  
Red Giant

Ratio of Horizontal Branch Stars to Red Giant Stars in Globular Clusters

Nature ◽  
1969 ◽  
Vol 224 (5223) ◽  
pp. 1006-1008 ◽  
Author(s):  
ICKO IBEN ◽  
ROBERT T. ROOD ◽  
KAREN M. STROM ◽  
STEPHEN E. STROM
Keyword(s):  
Globular Clusters ◽  
Horizontal Branch ◽  
Giant Stars ◽  
Horizontal Branch Stars ◽  
Red Giant Stars ◽  
Red Giant

scholarly journals On the Number Ratio of Horizontal Branch Stars to Red Giant Stars in Globular Clusters

1981 ◽  
Vol 93 ◽  
pp. 284-284
Author(s):  
N. Arimoto ◽  
M. Simoda
Keyword(s):  
Globular Clusters ◽  
Big Bang ◽  
Helium Abundance ◽  
Horizontal Branch ◽  
Giant Stars ◽  
Horizontal Branch Stars ◽  
Significant Difference ◽  
Red Giant Stars ◽  
The Difference ◽  
Red Giant

The number ratios of horizontal branch stars to red giant stars were obtained for globular clusters and Draco dwarf galaxy and the helium abundance was estimated using model results without semiconvection zone (SCZ) and with fully developed one. The analysis was confined to the four clusters (M4, M5, M13, and 47 Tuc) and the Draco galaxy, for which fairly precise star counts had been carried out. The effect of the difference in radial distribution between horizontal and red giant branch stars were taken into account, if necessary. The statistically significant difference in R exists among these objects. The cause may be the difference in the helium abundance and/or in the development of the SCZ. In the case of the fully developed SCZ, the helium abundance for M5 and Draco is appreciably smaller than the value given by the big-bang cosmology. It may be taken as an evidence against the full development of the SCZ for the horizontal branch stars in these objects.

Chemical Compositions of Red Giant Stars in Old Large Magellanic Cloud Globular Clusters

2006 ◽  
Vol 640 (2) ◽  
pp. 801-822 ◽  
Author(s):  
Jennifer A. Johnson ◽  
Inese I. Ivans ◽  
Peter B. Stetson
Keyword(s):  
Globular Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Chemical Compositions ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

Carbon abundances in red giant stars in the globular clusters M92 and NGC 6397

1979 ◽  
Vol 229 ◽  
pp. 604 ◽  
Author(s):  
R. A. Bell ◽  
R. J. Dickens ◽  
B. Gustafsson
Keyword(s):  
Globular Clusters ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

High-resolution spectra of stars in globular clusters. VI - Oxygen-deficient red giant stars in M13

1991 ◽  
Vol 101 ◽  
pp. 1693 ◽  
Author(s):  
Jeffery A. Brown ◽  
George Wallerstein ◽  
J. B. Oke
Keyword(s):  
High Resolution ◽  
Globular Clusters ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant

scholarly journals Precise radial velocities of giant stars

2020 ◽  
Vol 644 ◽  
pp. A1
Author(s):  
Marcelo Tala Pinto ◽  
Sabine Reffert ◽  
Andreas Quirrenbach ◽  
Stephan Stock ◽  
Trifon Trifonov ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Main Sequence ◽  
Evolutionary Stage ◽  
Horizontal Branch ◽  
Giant Stars ◽  
Horizontal Branch Stars ◽  
Formation And Evolution ◽  
Red Giant ◽  
Data Yield ◽  
Giant Branch Stars

Context. More than 100 exoplanets have been discovered around K and G giant stars, and their properties differ considerably from those of the planets found orbiting Sun-like and late-type main-sequence stars. This allows us to study the properties of planetary systems after the host star has evolved off the main-sequence, and it helps us to constrain planetary formation and evolution models. Aims. Our aim is to find out whether the long-period radial velocity variations observed in four giant stars of the Lick survey are caused by orbiting planets, and to study the properties of the planet population as a function of the stellar evolutionary stage. Methods. We analyzed 12 yr of precise radial velocity data for four stars of the Lick sample. In addition, we compared the planet frequency as a function of the evolutionary stage for two surveys, Lick and Express, based on the evolutionary stages derived using Bayesian inference. Results. We report the discovery of two new exoplanets and three exoplanet candidates orbiting giant stars. The best Keplerian fits to the data yield minimum masses of 2.5 MJ and 4.3 MJ for the planets orbiting HD 25723 and 17 Sco, respectively. The minimum masses of an additional candidate around HD 25723, and of planet candidates around 3 Cnc and 44 UMa, would be 1.3 MJ, 20.7 MJ, and 12.1 MJ, respectively. In addition, we compute planet frequencies for the Lick and Express samples as a function of the evolutionary stage. Within each sample, the planet frequency for the horizontal branch stars is the same as for the red giant branch stars. Conclusions. We have discovered two new exoplanets and three new exoplanet candidates, one of them being the second planet in a possible multi-planetary system. Based on our derived planet frequencies, we conclude that stellar evolution does not affect the number of observable planets between the red-giant and horizontal-branch evolutionary stages.

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