The oldest and most metal-poor stars are critical for our understanding of the early universe, because they carry the imprint of the first supernovae. Studying these stars in detail advances our understanding of the first generations of star formation and supernovae and the earliest period of galaxy formation. However, only a small fraction of the stars in the Galaxy are old and metal-poor, so finding them is not trivial. For a long time, the numbers of known extremely metal-poor stars were small.

However, this is changing. We are currently in the era of large scale surveys in most fields in Astronomy, and this is also the case for very metal-poor stars. There are dedicated surveys starting with metallicity-sensitive photometry which is subsequently followed up with spectroscopy (e.g. the Pristine and SkyMapper surveys). There are also efforts to find very metal-poor stars in existing, general surveys like SDSS (for example the TOPoS survey), RAVE, LAMOST and GALAH. Future large spectroscopic projects like WEAVE and 4MOST have dedicated sub-surveys for stars in the Galactic halo. Additionally, the next data release of Gaia will have (very) low resolution spectra of all bright stars which is potentially a goldmine of candidate very metal-poor stars. The European contribution to most of these surveys is significant.

All the different surveys together are expected to create an explosion in the number of known very/extremely/ultra metal-poor stars with low- and high-resolution spectra available. The goal of this session is to bring together people from the community and from different surveys, to coordinate our efforts and to think about how this large amount of data is going to change the field of metal-poor stars. What do we need to analyse all this data? Do the surveys have different focuses? What is the next-next step?

Programme

Invited speakers

• Vanessa Hill (OCA, France) (review surveys)
• David Aguado (Cambridge UK) (SDSS & low-resolution spectroscopy)
• Giuseppina Battaglia (IAC, Spain) (WEAVE)
• Chiara Battistini (LSW Heidelberg Germany) (4MOST)
• Sven Buder (MPIA, Germany) (GALAH)
• Elisabetta Caffau (Observatoire de Paris, France) (TOPoS)
• Morgan Fouesneau (MPIA, Germany) (Gaia)
• Nicolas Martin (University of Strasbourg, France / MPIA, Germany) (Pristine)
• Thomas Nordlander (ANU, Australia) (SkyMapper)

Scientific organisers

• Anke Arentsen (AIP, Germany)
• Nicolas Martin (University of Strasbourg, France / MPIA, Germany)
• Carlos Allende Prieto (IAC, Spain)
• Piercarlo Bonifacio (GEPI, France)
• Thomas Nordlander (ANU, Australia)
• Ása Skúladóttir (MPIA, Germany)

Contact

Anke Arentsen (aarentsen @ aip.de)