Clump formation through colliding stellar winds in the Galactic Centre
  The gas cloud G2 is currently being tidally disrupted by the Galactic Centre
super-massive black hole, Sgr A*. The region around the black hole is populated
by $\sim 30$ Wolf-Rayet stars, which produce strong outflows. We explore the
possibility that gas clumps, such as G2, originate from the collision of
stellar winds via the non-linear thin shell instability. Following an
analytical approach, we study the thermal evolution of slabs formed in the
symmetric collision of winds, evaluating whether instabilities occur, and
estimating possible clump masses. We find that the collision of relatively slow
($< 750$ km s$^{-1}$) and strong ($\sim 10^{-5}$ Msun yr$^{-1}$) stellar winds
from stars at short separations ($<10$ mpc) is a process that indeed could
produce clumps of G2's mass and above. Such short separation encounters of
single stars along their known orbits are not common in the Galactic Centre,
making this process a possible but unlikely origin for G2. We also discuss
clump formation in close binaries such as IRS 16SW and in asymmetric encounters
as promising alternatives that deserve further numerical study.
