S18B0152abst
S18B0152
Stars with unusual chemical abundances offer clues about rare astrophysical events or nucleosynthetic pathways. One such example are stars with significantly depleted magnesium and enhanced potassium ([Mg/Fe] < −1; [K/Fe] > 1). Stars with this strong signature have, to date, only been found in the globular cluster NGC 2419. The origin of this pattern remains unknown. Theoretical attempts to reproduce it require unrealistic temperature conditions and nuclear cross-sections orders of magnitude above laboratory measurements. Stars in NGC 2419 show a correlation between the abundances of light (e.g. Mg, K) and neutron-capture elements, which could point to the responsible mechanism, but so far only 5 Mg/K stars have detailed abundances measured. Chemical abundances are needed for more stars showing the Mg/K pattern to understand its peculiar origin. We have identified 112 Milky Way field stars with significantly enhanced [K/Fe] and depleted [Mg/Fe] from ∼500,000 giant stars in LAMOST. Our sample suggests that the mechanism responsible for peculiar abundances in NGC 2419 is not limited to globular clusters. We seek two grey nights with Subaru/HDS to observe 30 candidates in order to measure detailed abundances and understand the origin of this unexplained signature.
This document was translated from LATEX by HEVEA.