On the existence of a very metal-poor disc in the Milky Way

Understand

There has been a discussion for many years on whether the disc in the Milky Way extends down to low metallicity.

• We aim to address the question by employing a large sample of giant stars with radial velocities and homogeneous metallicities based on the Gaia DR3 XP spectra.
• We study the 3D velocity distribution of stars in various metallicity ranges, including the very-metal poor regime (VMP, [M/H] $<-2.0$).
• We find that a clear disc population starts to emerge only around [M/H] $\sim -1.3$, and is not visible for [M/H] $<-1.6$.