The Galactic Center cloud G2 and its gas streamer
  We present new, deep near-infrared SINFONI @ VLT integral field spectroscopy
of the gas cloud G2 in the Galactic Center, from late summer 2013 and spring
2014. G2 is visible in recombination line emission. The spatially resolved
kinematic data track the ongoing tidal disruption. As expected for an
observation near pericenter passage, roughly half of the gas in 2014 is found
at the redshifted, pre-pericenter side of the orbit, while the other half is at
the post-pericenter, blueshifted side. We also present an orbital solution for
the gas cloud G1, which was discovered a decade ago in L'-band images when it
was spatially almost coincident with Sgr A*. The orientation of the G1 orbit in
the three angles is almost identical to the one of G2, but it has a lower
eccentricity and smaller semi-major axis. We show that the observed astrometric
positions and radial velocities of G1 are compatible with the G2 orbit,
assuming that (i) G1 was originally on the G2 orbit preceding G2 by 13 years
and (ii) a simple drag force acted on it during pericenter passage. Taken
together with the previously described tail of G2, which we detect in
recombination line emission and thermal broadband emission, we propose that G2
may be a bright knot in a much more extensive gas streamer. This matches purely
gaseous models for G2, such as a stellar wind clump or the tidal debris from a
partial disruption of a star.
