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Table 1

Amount of He enhancement of M3 BHB stars compared to RHB stars.

Phase Teff range [K] ΔY % non-variables % total HB Main diagnostic

RHB+V <7500 <0.01 32 ± 5% 58 ± 6% Strömgren (visual)
cool BHB 7500 ↔ 8300 0.01 21 ± 4% 13 ± 3% Strömgren (visual)
BHB 8300 ↔ 9300 <0.02 25 ± 4% 15 ± 3% WFPC2 (near UV)
hot BHB 9300 ↔ 10 900 0.02 16 ± 3% 10 ± 2% WFPC2 (near UV)
eBHB >10 900 ? 6 ± 2% 4 ± 1%

Notes. Fractions are calculated considering only non-variable stars and that the total HB population follows a relation B:V:R = 0.47:0.37:0.16, where B, V, R stand for the number of blue, variable (RR Lyrae), and red HB stars, respectively (Catelan et al. 2001).

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