We present Magellan/IMACS , Anglo-Australian Telescope/AAOmega+2dF , and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the Carina II ( Car II ) & Carina III ( Car III ) dwarf galaxy candidates , recently discovered in the Magellanic Satellites Survey ( MagLiteS ) .
We identify 18 member stars in Car II , including 2 binaries with variable radial velocities and 2 RR Lyrae stars .
The other 14 members have a mean heliocentric velocity v _ { hel } = 477.2 \pm 1.2 \mathrm { km } \mathrm { s } ^ { -1 } and a velocity dispersion of \sigma _ { v } = 3.4 ^ { +1.2 } _ { -0.8 } \mathrm { km } \mathrm { s } ^ { -1 } .
Assuming Car II is in dynamical equilibrium , we derive a total mass within the half-light radius of 1.0 ^ { +0.8 } _ { -0.4 } \times 10 ^ { 6 } \mathrm { M _ { \odot } } , indicating a mass-to-light ratio of 369 ^ { +309 } _ { -161 } \mathrm { M _ { \odot } } / \mathrm { L _ { \odot } } .
From equivalent width measurements of the calcium triplet lines of 9 RGB stars , we derive a mean metallicity of \mbox { [ Fe / H ] } = -2.44 \pm 0.09 with dispersion \sigma _ { \mbox { [ Fe / H ] } } = 0.22 ^ { +0.10 } _ { -0.07 } .
Considering both the kinematic and chemical properties , we conclude that Car II is a dark-matter-dominated dwarf galaxy .
For Car III , we identify 4 member stars , from which we calculate a systemic velocity of v _ { hel } = 284.6 ^ { +3.4 } _ { -3.1 } \mathrm { km } \mathrm { s } ^ { -1 } .
The brightest RGB member of Car III has a metallicity of \mbox { [ Fe / H ] } = -1.97 \pm 0.12 .
Due to the small size of the Car III spectroscopic sample , we can not conclusively determine its nature .
Although these two systems have the smallest known physical separation ( \Delta d \sim 10 ~ { } \mathrm { kpc } ) among Local Group satellites , the large difference in their systemic velocities , \sim 200 ~ { } \mathrm { km } \mathrm { s } ^ { -1 } , indicates that they are unlikely to be a bound pair .
One or both systems are likely associated with the Large Magellanic Cloud ( LMC ) , and may remain LMC satellites today .
No statistically significant excess of \gamma -ray emission is found at the locations of Car II and Car III in eight years of Fermi -LAT data .