science

The usual place to look for metal-poor stars in the Galaxy is the halo or in dwarf galaxies, but many of the oldest, metal-poor stars are actually expected in the inner part of the Milky Way, overlapping with the Galactic bulge. Since 2017, I have been leading a project called the Pristine Inner Galaxy Survey (PIGS) to find and study these ancient inner Galaxy stars. It is a project within the Pristine collaboration, which uses narrow-band CaHK photometry from the Canada-France-Hawaii Telescope to efficiently pre-select metal-poor stars. Over the years, we have followed up many stars with low/medium-resolution and high-resolution spectroscopy and studied their chemo-dynamical properties - see the publications list on the Pristine website. 

I am also interested in the detailed properties of the most metal-poor stars. One interesting subtype of metal-poor stars are the carbon-enhanced metal-poor (CEMP) stars, which are ever more ubiquitous at lower metallicities. Some of these CEMP stars can be explained by binary mass-transfer from a former asymptotic giant branch (AGB) companion, but the most metal-poor ones often do not show those AGB signatures and need to be explained in other ways: they were likely born with their peculiar abundance pattern. I've worked on the binary properties of CEMP stars, investigated their occurrence in the inner Galaxy, reviewed the recent literature and methodologies to analyse low-resolution spectra of CEMP stars, and studied their population using Gaia XP spectra. 

I am looking forward to the new data coming out of the large spectroscopic surveys WEAVE and 4MOST, to shed new light on the properties of the ancient inner Galaxy and the populations of metal-poor stars throughout the entire Milky Way.