We present tentative evidence for the existence of a dissolved star cluster in the Sextans dwarf spheroidal galaxy .
In a sample of six stars , we identify three ( possibly four ) stars around [ \mathrm { Fe } / \mathrm { H } ] = -2.7 that are highly clustered in a multi-dimensional chemical abundance space .
The estimated initial stellar mass of the cluster is M _ { *, \mathrm { init } } = 1.9 ^ { +1.5 } _ { -0.9 } ~ { } ( 1.6 ^ { +1.2 } _ { -0.8 } ) \times 10 ^ { 5 } ~ { } % \mathcal { M _ { \odot } } assuming a Salpeter ( Kroupa ) initial mass function ( IMF ) .
If corroborated by follow-up spectroscopy , this ancient star cluster at [ \mathrm { Fe } / \mathrm { H } ] = -2.7 is the most metal-poor system identified to date .
Inspired by this finding , we also present a new way to interpret the cumulative metallicity functions of dwarf galaxies .
From available observational data , we speculate that the ultra-faint dwarf galaxy population , or a significant fraction thereof , and the more luminous , classical dwarf spheroidal population were formed in different environments and would thus be distinct in origin .