On the Hunt for the Origins of the Orphan-Chenab Stream: Detailed Element Abundances with APOGEE and Gaia

Published version
Repository DOI

Change log

jats:titleAbstract</jats:title> jats:pStellar streams in the Galactic halo are useful probes of the assembly of galaxies like the Milky Way. Many tidal stellar streams that have been found in recent years are accompanied by a known progenitor globular cluster or dwarf galaxy. However, the Orphan–Chenab (OC) stream is one case where a relatively narrow stream of stars has been found without a known progenitor. In an effort to find the parent of the OC stream, we use astrometry from the early third data release of ESA’s Gaia mission (Gaia EDR3) and radial velocity information from the Sloan Digital Sky Survey (SDSS)-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey to find up to 13 stars that are likely members of the OC stream. We use the APOGEE survey to study the chemical nature (for up to 10 stars) of the OC stream in the jats:italicα</jats:italic> (O, Mg, Ca, Si, Ti, and S), odd-jats:italicZ</jats:italic> (Al, K, and V), Fe-peak (Fe, Ni, Mn, Co, and Cr), and neutron-capture (Ce) elemental groups. We find that the stars that make up the OC stream are not consistent with a monometallic population and have a median metallicity of −1.92 dex with a dispersion of 0.28 dex. Our results also indicate that the α elements are depleted compared to the known Milky Way populations and that its [Mg/Al] abundance ratio is not consistent with second-generation stars from globular clusters. The detailed chemical pattern of these stars, namely the [jats:italicα</jats:italic>/Fe]–[Fe/H] plane and the metallicity distribution, indicates that the OC stream progenitor is very likely to be a dwarf spheroidal galaxy with a mass of ∼10jats:sup6</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub>.</jats:p>

5109 Space Sciences, 5101 Astronomical Sciences, 51 Physical Sciences
Journal Title
Astrophysical Journal
Conference Name
Journal ISSN
Volume Title
American Astronomical Society
National Science Foundation (NSF) (AST-1907417)
National Science Foundation (NSF) (AST-2108736)