The Metal-poor non-Sagittarius (?) Globular Cluster NGC 5053: Orbit and
  Mg, Al and Si Abundances
  Metal-poor globular clusters (GCs) exhibit intriguing Al-Mg anti-correlations
and possible Si-Al correlations, which are important clues to decipher the
multiple-population phenomenon. NGC 5053 is one of the most metal-poor GCs in
the nearby Universe, and has been suggested to be associated with the
Sagittarius (Sgr) dwarf galaxy, due to its similarity in location and radial
velocity with one of the Sgr arms. In this work, we simulate the orbit of NGC
5053, and argue against a physical connection between Sgr and NGC 5053. On the
other hand, the Mg, Al, and Si spectral lines, which are difficult to detect in
the optical spectra of NGC 5053 stars, have been detected in the near-infrared
APOGEE spectra. We use three different sets of stellar parameters and codes to
derive the Mg, Al, and Si abundances. Regardless of which method is adopted, we
see a large Al variation, and a substantial Si spread. Along with NGC 5053,
metal-poor GCs exhibit different Mg, Al, and Si variations. Moreover, NGC 5053
has the lowest cluster mass among the GCs that have been identified to exhibit
an observable Si spread until now.
