OGLE-III detection of the anomalous galactic bulge red giant branch bump: Evidence of enhanced helium enrichment
We measure the red giant branch bump (RGBB) of the Galactic bulge, the most metal-rich RGBB ever detected. The RGBB luminosity function peaks at the expected brightness, but its number density is very low relative to Galactic globular cluster calibrations, implying the Galactic bulge has a higher helium enrichment parameter ΔY/ΔZ ≥ 4.0 for Y 0.35 rather than the standard 2.0 with Y = 0.27, which we suggest may be a common feature of galactic spheroids. The RGBB is (0.71 0.02) mag fainter than...[Show more]
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|Source:||Astrophysical Journal, The|
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