EFFECTS OF α-ELEMENT ENHANCEMENT AND THE THERMALLY PULSING-ASYMPTOTIC GIANT BRANCH ON SURFACE BRIGHTNESS FLUCTUATION MAGNITUDES AND BROADBAND COLORS

2009/02/28 by Hyun-chul Lee, Guy Worthey, John P. Blakeslee
Physics and Astronomy · #Astronomy and Astrophysical Research #Brightness #Broadband #Giant star #Red giant #Red-giant branch #Scientific Research and Discoveries #Stars #Stellar, planetary, and galactic studies #Surface brightness #astro-ph.CO #astro-ph.SR

paper · pdf · doi:10.1088/0004-637x/710/1/421

published as Astrophys.J.710:421-431,2010 · Accepted for publication in the Astrophysical Journal, 15 figures

arxiv created 2009/12/11 · openalex publication_date 2010/01/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06

Abstract

We investigate the effects of α-element enhancement and the thermally pulsing-asymptotic giant branch (TP-AGB) stars on the surface brightness fluctuation (SBF) magnitudes and broadband colors of simple stellar populations and compare to the empirical calibrations. We consider a broad range of ages and metallicities using the recently updated Teramo BaSTI isochrones. We find that the α-element-enhanced I -band SBF magnitudes are about 0.35 mag brighter and their integrated V − I colors are about 0.02 mag redder, mostly because of oxygen-enhancement effects on the upper red giant branch and AGB. We also demonstrate, using both the Teramo BaSTI and Padova isochrones, the acute sensitivity of SBF magnitudes to the presence of TP-AGB stars, particularly in the near-IR, but in the I band as well. Empirical SBF trends therefore hold great promise for constraining this important but still highly uncertain stage of stellar evolution. In a similar vein, non-negligible disparities are found among several different models available in the literature due to intrinsic model uncertainties.

Citations

• Stellar population models of Lick indices with variable element abundance ratios
• Spectrophotometric Evolution of Old Stellar Systems
• Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
• The Dartmouth Stellar Evolution Database
• NEAR-INFRARED PHOTOMETRY OF FOUR STELLAR CLUSTERS IN THE SMALL MAGELLANIC CLOUD
• Measuring Distances and Probing the Unresolved Stellar Populations of Galaxies Using Infrared Surface Brightness Fluctuations
• Final Results from theHubble Space TelescopeKey Project to Measure the Hubble Constant
• Asymptotic Giant Branch Evolution and Beyond
• Evidence for TP‐AGB Stars in High‐Redshift Galaxies, and Their Effect on Deriving Stellar Population Parameters
• On the Age and Metallicity Estimation of Spiral Galaxies Using Optical and Near‐Infrared Photometry
• Low‐Temperature Opacities
• Galactic Stellar and Substellar Initial Mass Function
• Evolution of asymptotic giant branch stars