Kavli Affiliate: Alexander P. Ji
| First 5 Authors: Kaia R. Atzberger, Sam A. Usman, Alexander P. Ji, Lara R. Cullinane, Denis Erkal
| Summary:
Chemical abundances of stellar streams can be used to determine the nature of
a stream’s progenitor. Here we study the progenitor of the recently discovered
Leiptr stellar stream, which was previously suggested to be a tidally disrupted
halo globular cluster. We obtain high-resolution spectra of five red giant
branch stars selected from the Gaia DR2 STREAMFINDER catalog with
Magellan/MIKE. One star is a clear non-member. The remaining four stars display
chemical abundances consistent with those of a low-mass dwarf galaxy: they have
a low mean metallicity, $langle{rm[Fe/H]}rangle = -2.2$; they do not all
have identical metallicities; and they display low [$alpha$/Fe] $sim 0$ and
[Sr/Fe] and [Ba/Fe] $sim -1$. This pattern of low $alpha$ and neutron-capture
element abundances is only found in intact dwarf galaxies with stellar mass
$lesssim 10^5 M_odot$. Although more data are needed to be certain, Leiptr’s
chemistry is consistent with being the lowest-mass dwarf galaxy stream without
a known intact progenitor, possibly in the mass range of ultra-faint dwarf
galaxies. Leiptr thus preserves a record of one of the lowest-mass early
accretion events into the Milky Way.
| Search Query: ArXiv Query: search_query=au:”Alexander P. Ji”&id_list=&start=0&max_results=3