Massive stars in extremely metal-poor galaxies: a window into the past

Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. MG and FN acknowledge financial support through Spanish grants ESP2017-86582-C4-1-R and PID2019-105552RB-C41 (MCIU/AEI/FEDER) and from the Spanish State Research Agency (AEI) through the Unidad de Excelencia “Maria de Maeztu” – Centro de Astrobiologia (CSIC-INTA) project number MDM-2017-0737. AH acknowledges support by grants PGC-2018-091 3741-B-C22 and SEV 2015-0548, and by the Canarian Agency for Research, Innovation and Information Society (ACIISI), of the Canary Islands Government, and the European Regional Development Fund (ERDF), under grant ProID2017010115. SdM acknowledges the Netherlands Organisation for Scientific Research (Vidi grant BinWaves 639.042.728). D.Sz. has been supported by the Alexander von Humboldt Foundation.