Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the
  Galactic Center Black Hole
  We analyse and report in detail new near-infrared (1.45 - 2.45 microns)
observations of the Dusty S-cluster Object (DSO/G2) during its approach to the
black hole at the center of the Galaxy that were carried out with ESO
VLT/SINFONI between February and September 2014. Before May 2014 we detect
spatially compact Br-gamma and Pa-alpha line emission from the DSO at about
40mas east of SgrA*. The velocity of the source, measured from the red-shifted
emission, is 2700+-60 km/s. No blue-shifted emission above the noise level is
detected at the position of SgrA* or upstream the presumed orbit. After May we
find spatially compact Br-gamma blue-shifted line emission from the DSO at
about 30mas west of SgrA* at a velocity of -3320+-60 km/s and no indication for
significant red-shifted emission. We do not detect any significant extension of
velocity gradient across the source. We find a Br-gamma-line full width at half
maximum of 50+-10 Angstroem before and 15+-10 Angstroem after the peribothron
transit, i.e. no significant line broadening with respect to last year is
observed. Br-gamma line maps show that the bulk of the line emission originates
from a region of less than 20mas diameter. This is consistent with a very
compact source on an elliptical orbit with a peribothron time passage in
2014.39+-0.14. For the moment, the flaring activity of the black hole in the
near-infrared regime has not shown any statistically significant increment.
Increased accretion activity of SgrA* may still be upcoming. We discuss details
of a source model according to which the DSO is rather a young accreting star
than a coreless gas and dust cloud.
