Chemical tagging can work: Identification of stellar phase-space structures purely by chemical-abundance similarity

Understand

Chemical tagging promises to use detailed abundance measurements to identify spatially separated stars that were in fact born together (in the same molecular cloud), long ago.

• This idea has not yielded much practical success, presumably because of the noise and incompleteness in chemical-abundance measurements.
• We have succeeded in substantially improving spectroscopic measurements with The Cannon, which has now delivered 15 individual abundances for ~100,000 stars observed as part of the APOGEE spectroscopic survey, with precisions around 0.04 dex.
• We test the chemical-tagging hypothesis by looking at clusters in abundance space and confirming that they are clustered in phase space.