How Many Elements Matter?

Understand

Some studies of stars' multi-element abundance distributions suggest at least 5-7 significant dimensions, but others show that many elemental abundances can be predicted to high accuracy from [Fe/H] and [Mg/Fe] (or [Fe/H] and age) alone.

• We show that both propositions can be, and are, simultaneously true.
• We adopt a machine learning technique known as normalizing flow to reconstruct the probability distribution of Milky Way disk stars in the space of 15 elemental abundances measured by APOGEE.
• Conditioning on Teff and log g minimizes the differential systematics.