Exploring the Upper Red Giant and Asymptotic Giant Branches: the Globular Cluster M5

Abstract

We have tabulated lists of upper red giant, horizontal, and asymptotic giant branch (RGB, HB, AGB) stars in the globular cluster M5 that are complete to over 10' from the core for the RGB and AGB samples, and 8' for the HB sample. The large samples give us the most precise value of R_2 = N_AGB / N_HB to date for a single globular cluster (0.176 +/- 0.018). This is incompatible with theoretical calculations using the most recent physical inputs. The discrepancy can probably be attributed to the dependence of observed R_2 values on horizontal branch morphology. We identify the cluster M55 as being another possible example of this effect. Samples of HB and AGB stars in populous clusters may provide a means of calibrating the masses of horizontal branch stars in globular clusters. The cumulative luminosity function of the upper red giant branch shows an apparent deficit of observed stars near the tip of the branch. This feature has less than a 2% chance of being due to statistical fluctuations. The slope of the cumulative luminosity function for AGB stars is consistent with the theoretically predicted value from stellar models when measurement bias is taken into account. We also introduce a new diagnostic R_clump that reflects the fraction of the AGB lifetime that a star spends in the AGB clump. For M5, we find R_clump = 0.42 +/- 0.05, in marginal disagreement with theoretical predictions. Finally, we note that the blue half of M5's instability strip (where first overtone RR Lyraes reside) is underpopulated, based on the large numbers of fundamental mode RR Lyraes and on the nonvariable stars at the blue end of the instability strip. This fact may imply that the evolutionary tracks (and particularly the colors) of stars in the instability strip are affected by pulsations.

43 pages, 16 figures, accepted for publication in ApJ

References in corpus (25)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Abundances for Globular Cluster Giants: I. Homogeneous Metallicities for 24 Clusters
• A standard stellar library for evolutionary synthesis: II. The M dwarf extension
• Variable Stars in Galactic Globular Clusters
• Ultraviolet Radiation from Evolved Stellar Populations -- I. Models
• The YY Isochrones for alpha-element Enhanced Mixtures
• The giant, horizontal and asymptotic branches of galactic globular clusters. I. The catalog, photometric observables and features
• HST color-magnitude diagrams of 74 galactic globular clusters in the HST F439W and F555W bands
• Standard and Non-Standard Plasma Neutrino Emission Revisited
• The initial Helium content of Galactic Globular Cluster stars from the R-parameter: comparison with the CMB constraint
• The chemical composition of White Dwarfs as a test of convective efficiency during core He-burning
• Blue Straggler Stars: The Spectacular Population in M80
• The Second-Parameter Effect in Metal-Rich Globular Clusters
• CCD Photometry of the Globular Cluster M5. I. The Color-Magnitude Diagram and Luminosity Functions
• Bimodality and Gaps on Globular Cluster Horizontal Branches. II. The Cases of NGC 6229, NGC 1851 and NGC 2808
• Horizontal-Branch Models and the Second-Parameter Effect. III. The Impact of Mass Loss on the Red Giant Branch, and the Case of M5 and Palomar 4/Eridanus
• Horizontal-Branch Models and the Second-Parameter Effect. IV. The Case of M3 and Palomar 3
• Asymptotic Giant Branch predictions: theoretical uncertainties
• Variable Stars in the Globular Cluster M5. Application of the Image Subtraction Method
• RR Lyrae variables in Galactic globular clusters - I: The observational scenario
• A Catalog of Helium Abundance Indicators from Globular Cluster Photometry
• RR Lyrae variables in M5 as a test of pulsational theory
• CCD PHOTOMETRY OF RR LYRAE STARS IN M5 AS A TEST FOR THE PULSATIONAL SCENARIO
• Detection of the evolutionary stages of variables in M3
• UBV stellar photometry of bright stars in GC M5. I. UV colour-magnitude and colour-colour diagrams and some peculiarities in the HB stellar distribution

Cited by in corpus (23)

• Neutrino and axion bounds from the globular cluster M5 (NGC 5904)
• The fraction of second generation stars in Globular Clusters from the analysis of the Horizontal Branch
• The SEGUE K giant survey II: A Catalog of Distance Determinations for the SEGUE K giants in the Galactic Halo
• Particle-physics constraints from the globular cluster M5: Neutrino Dipole Moments
• Sodium content as a predictor of the advanced evolution of globular cluster stars
• The treatment of mixing in core helium burning models -- II. Constraints from cluster star counts
• AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)
• Precision Astrometry with Adaptive Optics
• Chemical Abundances for Evolved Stars in M5: Lithium through Thorium
• On the missing second generation AGB stars in NGC6752
• A Re-Evaluation of the Evolved Stars in the Globular Cluster M13
• A differential chemical abundance scale for the globular cluster M5
• The Blue Straggler Population of the Globular Cluster M5: Comparison with M3
• Evolved Stars in the Core of the Massive Globular Cluster NGC 2419
• Wide-field multi-color photometry of the Galactic globular cluster NGC 1261
• The Pattern of CN, O, and Na Inhomogeneities on the Red Giant Branch of Messier 5
• A Robust Test of Evolution near the Tip of the Red Giant Branch and Missing Giants in NGC 2808
• Slowly cooling white dwarfs in NGC 6752
• Multi-Color Photometry of the Galactic Globular Cluster M75 = NGC 6864. A New Sensitive Metallicity Indicator and the Position of the Horizontal Branch in UV
• Different Characteristics of the Bright Branches of the Globular Clusters M3 and M13
• Carbon Abundance Inhomogeneities and Deep Mixing Rates in Galactic Globular Clusters
• The Populations of Carina. I. Decoding the Color--Magnitude Diagram
• On the impossible NGC 4372 V1 and V2: an extended AGB to the [Fe/H] = -2.2 cluster