Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2

Abstract We present the kinematic and chemical profiles of red giant stars observed by Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2 survey in direction Jhelum stellar stream, a Milky Way substructure located inner halo at distance from Sun ≈13 kpc. From six APOGEE-2 pointings, we isolate with log( g ) < 3.5, leaving sample 289 stars. this giants, identified seven that are consistent astrometric signal Gaia DR2 for stream. Of these seven, one falls onto branch (RGB) along same sequence as presented Ji et al. This new member has [Fe/H] = −2.2 is tip RGB. By selecting high orbital eccentricity, metal-rich stars, identify giants our APOGEE2 likely associated Gaia-Enceladus-Sausage (GES) merger. compare abundance GES find similar trends α -elements, expected low-metallicity populations. However, orbits not generally shared origin. The abundances star other confirmed members stream to known streams thus an accreted dwarf galaxy origin progenitor although cannot rule out globular cluster