Abundance analysis of the Cetus stellar stream: open questions for further studies

Abstract

Dwarf galaxy streams encode vast amounts of information essential to understanding early galaxy formation and nucleosynthesis channels. From detailed chemical composition of 22 Cetus stream’s stars, we learned that the Cetus progenitor was likely a classical dwarf spheroidal galaxy that ceased chemical evolution after the main s-process production began in intermediate-mass asymptotic giant branch stars, but before iron production from type Ia supernovae became substantial. Despite these insights, many questions about the details of chemical evolution in the Cetus progenitor remain unresolved. The nature of the Cetus is not clearly understood until getting robust conclusions about a lack of carbon enhanced metal-poor stars, a source(s) of Sr production at the earliest stage, a possible distinct behavior of neutron-capture elements in the Cetus-New and Cetus-Palca wraps, an origin of sodium-enhanced Cetus stars, and a hint of an “ α -knee”. To address these puzzles, further observations of additional Cetus stream members are required.