Spatially Resolved X-ray Spectroscopy of Vela Shrapnel A
  We present the detailed X-ray spectroscopy of Vela shrapnel A with the XMM-Newton satellite. Vela shrapnel A is one of several protrusions identified as bullets from Vela supernova explosion. The XMM-Newton image shows that shrapnel A consists of a bright knot and a faint trailing wake. We extracted spectra from various regions, finding a prominent Si Ly$_\alpha$ emission line in all the spectra. All the spectra are well represented by the non-equilibrium ionization (NEI) model. The abundances are estimated to be O$\sim$0.3, Ne$\sim$0.9, Mg$\sim$0.8, Si$\sim$3, Fe$\sim$0.8 times their solar values. The non-solar abundance ratio between O and Si indicates that shrapnel A originates from a deep layer of a progenitor star. We found that the relative abundances between heavy elements are almost uniform in shrapnel A, which suggests that the ejecta from supernova explosion are well mixed with swept-up interstellar medium. 
S. Katsuda and H. Tsunemi