Deep VLT photometry of the faint stellar system in the Large Magellanic
  Cloud periphery YMCA-1
  We present FORS2@VLT follow-up photometry of YMCA-1, a recently discovered
stellar system located 13\degr~from the Large Magellanic Cloud (LMC) center.
The deep color-magnitude diagram (CMD) reveals a well-defined main sequence
(MS) and a handful of stars in the post-MS evolutionary phases. We analyse the
YMCA-1 CMD by means of the automated isochrone matching package {\tt ASteCA}
and model its radial density profile with a Plummer function. We find that
YMCA-1 is an old ($11.7^{+1.7}_{-1.3}$~Gyr), metal-intermediate ([Fe/H] $\simeq
-1.12^{+0.21}_{-0.13}$~dex), compact (r$_{\rm h} = 3.5 \pm 0.5$ pc), low-mass
(M $= 10^{2.45 \pm 0.02} M_{\odot}$) and low-luminosity (M$_V = -0.47 \pm
0.57$~mag) stellar system. The estimated distance modulus ($\mu_0 =
18.72^{+0.15}_{-0.17}$~mag), corresponding to about 55~kpc, suggests that
YMCA-1 is associated to the LMC, but we cannot discard the scenario in which it
is a Milky Way satellite. The structural parameters of YMCA-1 are remarkably
different compared with those of the 15 known old LMC globular clusters. In
particular, it resides in a transition region of the M$_V$-r$_h$ plane, in
between the ultra-faint dwarf galaxies and the classical old clusters, and
close to SMASH-1, another faint stellar system recently discovered in the LMC
surroundings.
