The Distribution of Mass in the Orion Dwarf Galaxy
  Dwarf galaxies are good candidates to investigate the nature of Dark Matter,
because their kinematics are dominated by this component down to small
galactocentric radii. We present here the results of detailed kinematic
analysis and mass modelling of the Orion dwarf galaxy, for which we derive a
high quality and high resolution rotation curve that contains negligible
non-circular motions and we correct it for the asymmetric drift. Moreover, we
leverage the proximity (D = 5.4 kpc) and convenient inclination (47{\deg}) to
produce reliable mass models of this system. We find that the Universal
Rotation Curve mass model (Freeman disk + Burkert halo + gas disk) fits the
observational data accurately. In contrast, the NFW halo + Freeman disk + gas
disk mass model is unable to reproduce the observed Rotation Curve, a common
outcome in dwarf galaxies. Finally, we attempt to fit the data with a MOdified
Newtonian Dynamics (MOND) prescription. With the present data and with the
present assumptions on distance, stellar mass, constant inclination and
reliability of the gaseous mass, the MOND "amplification" of the baryonic
component appears to be too small to mimic the required "dark component". The
Orion dwarf reveals a cored DM density distribution and a possible tension
between observations and the canonical MOND formalism.
