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The first stars are predicted to have formed within 200 million years afterthe Big Bang, initiating the cosmic dawn. A true first star has not yet beendiscovered, although stars with tiny amounts of elements heavier than helium('metals') have been found in the outer regions ('halo') of the Milky Way. Thefirst stars and their immediate successors should, however, preferentially befound today in the central regions ('bulges') of galaxies, because they formedin the largest over-densities that grew gravitationally with time. The MilkyWay bulge underwent a rapid chemical enrichment during the first 1-2 billionyears, leading to a dearth of early, metal-poor stars. Here we reportobservations of extremely metal-poor stars in the Milky Way bulge, includingone star with an iron abundance about 10,000 times lower than the solar valuewithout noticeable carbon enhancement. We confirm that the most metal-poorbulge stars are on tight orbits around the Galactic Centre, rather than beinghalo stars passing through the bulge, as expected for stars formed at redshiftsgreater than 15. Their chemical compositions are in general similar to typicalhalo stars of the same metallicity although intriguing differences exist,including lower abundances of carbon.

Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way