EFFECTS OF alpha-ELEMENT ENHANCEMENT AND THE THERMALLY PULSING-ASYMPTOTIC GIANT BRANCH ON SURFACE BRIGHTNESS FLUCTUATION MAGNITUDES AND BROADBAND COLORS
- Department of Physics and Geology, University of Texas-Pan American, Edinburg, TX 78539 (United States)
We investigate the effects of alpha-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 alpha-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.
- OSTI ID:
- 21394505
- Journal Information:
- Astrophysical Journal, Vol. 710, Issue 1; Other Information: DOI: 10.1088/0004-637X/710/1/421; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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