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I will discuss the results of a search for extremely metal-poor stars based on SkyMapper data release DR1.1. The search process involves photometric selection and low-resolution spectroscopic follow-up at the 2.3m that provides estimates of effective temperature, surface gravity and metallicity ([Fe/H]) for the candidates. The selection process is very efficient: for the 2618 candidates with 2.3m spectra that have photometric metallicities <_ -2.0, 41% have [Fe/H] <_ -2.75 and only ~7% have [Fe/H] > -2.0. The most metal-poor candidate has [Fe/H] < -4.75 and is notably C-rich. We find that the metallicity distribution function for the observed sample, which is dominated by ’carbon-normal’ stars, has a power-law slope of Delta(log N)/Delta([Fe/H]) = 1.5 +/- 0.1 for -4.0 <_ [Fe/H] <_ -2.75, but appears to drop abruptly at [Fe/H] ~ -4.2 in line with previous studies. The small fraction of stars below this limit are all C-rich. |
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