Blueshifted Brγ line maps of the GC at 2.164 μm (left) that are based on the data sets of 2006, 2012, and 2015. The green contour lines are extracted from the K-band continuum emission of the associated data cubes. Sgr A* is located at the cross, the S star S2 is labeled. The arrow points toward the position of X8 in the blueshifted Brγ line maps in 2006, 2012, and 2015. The cross is centered on SgrA* in every year. The arrow is fixed on the position of X8 in 2006 to show the proper motion. On the right side, the K-band spectrum between 2.0 μm–2.4 μm of X8 is presented. The intensity is given in arbitrary units (a.u.), and the blueshifted HeI and Brγ line are framed with a dashed line. The spectrum of 2012 and 2015 shows the blueshifted [Fe III] multiplet ³G − ³H at 2.1410 μm, 2.2142 μm, 2.2379 μm, and 2.3436 μm.