  The Vela supernova remnant (SNR) shows several ejecta fragments protruding
beyond the forward shock (shrapnel). Recent studies have revealed high Si
abundance in two shrapnel (A and G), located in opposite directions with
respect to the SNR center. This suggests the possible existence of a Si-rich
jet-counterjet structure. We analyzed an XMM-Newton observation of a bright
clump, behind shrapnel G, which lies along the direction connecting A and G.
The aim is to study the physical and chemical properties of this clump to
ascertain whether it is part of this putative jet-like structure. We produced
background-corrected and adaptively-smoothed count-rate images and median
photon energy maps, and performed a spatially resolved spectral analysis. We
identified two structures with different physical properties. The first one is
remarkably elongated along the direction connecting A and G. Its X-ray spectrum
is much softer than that of the other two shrapnel, to the point of hindering
the determination of the Si abundance, however its physical and chemical
properties are consistent with those of shrapnel A and G. The second structure,
running along the southeast-northwest direction, has a higher temperature and
appears like a thin filament. By analyzing the ROSAT data, we have found that
this filament is part of a very large and coherent structure that we identified
in the western rim of the shell. We obtained a thorough description of the tail
of Shrapnel G. In addition we discovered a coherent and very extended feature
that we interpret as a signature of an earlier interaction of the remnant with
the stellar wind of its progenitor star. The peculiar Ne/O ratio we found in
the wind residual may be suggestive of a Wolf-Rayet progenitor for Vela SNR,
though further analysis is required to address this point.
