  Context. PDS 70 is a young (5.4 Myr), nearby (~113 pc) star hosting a known
transition disk with a large gap. Recent observations with SPHERE and NACO in
the near-infrared (NIR) allowed us to detect a planetary mass companion,
PDS70b, within the disk cavity. Moreover, observations in H_alpha with MagAO
and MUSE revealed emission associated to PDS70b and to another new companion
candidate, PDS70c, at a larger separation from the star. Aims. Our aim is to
confirm the discovery of the second planet PDS70c using SPHERE at VLT, to
further characterize its physical properties, and search for additional point
sources in this young planetary system. Methods. We re-analyzed archival SPHERE
NIR observations and obtained new data in Y, J, H and K spectral bands for a
total of four different epochs. The data were reduced using the data reduction
and handling pipeline and the SPHERE data center. We then applied custom
routines (e.g. ANDROMEDA and PACO) to subtract the starlight. Results. We
re-detect both PDS 70 b and c and confirm that PDS70c is gravitationally bound
to the star. We estimate this second planet to be less massive than 5 M Jup and
with a T_eff around 900 K. Also, it has a low gravity with log g between 3.0
and 3.5 dex. In addition, a third object has been identified at short
separation (~0.12") from the star and gravitationally bound to the star. Its
spectrum is however very blue, so that we are probably seeing stellar light
reflected by dust and our analysis seems to demonstrate that it is a feature of
the inner disk. We, however, cannot completely exclude the possibility that it
is a planetary mass object enshrouded by a dust envelope. In this latter case,
its mass should be of the order of few tens of M_Earth. Moreover, we propose a
possible structure for the planetary system based on our data that, however,
cannot be stable on a long timescale.
