A Detailed Archival CHANDRA Study of the Young Core-Collapse Supernova
  Remnant 1E 0102.2-7219 in the Small Magellanic Cloud
  We present an archival Chandra study of the O-rich supernova remnant (SNR) 1E
0102.2-7219 in the Small Magellanic Cloud. Based on the deep $\sim$ 265 ks
archival Chandra data we performed a detailed spatially resolved spectral
analysis of 1E 0102.2-7219. Our aim is to reveal the spatial and chemical
structures of this remnant in unprecedented details. Radial profiles of O, Ne
and Mg abundances based on our analysis of regional spectra extracted along
nine different azimuthal directions of 1E 0102.2-7219 suggest the contact
discontinuity at $\sim$ 5-5.5 pc from the geometric center of the X-ray
emission of the SNR. We find that the metal-rich ejecta gas extends further
outward in west and southwest than in other directions of the SNR. The average
O/Ne, O/Mg and Ne/Mg abundance ratios of the ejecta are in plausible agreement
with the nucleosynthesis products from the explosion of a $\sim 40 M_\odot$
progenitor. We estimate an upper limit on the Sedov age of $\sim 3500$ yr and
explosion energy of $\sim 1.8\times10^{51}$ erg for 1E 0102.2-7219. We discuss
the implications of our results on the geometrical structure of the remnant,
its circumstellar medium and the nature of the progenitor star. Our results do
not fit with a simple picture of the reverse-shocked emission from a spherical
shell-like ejecta gas with a uniformly-distributed metal abundance and a
power-law density along the radius of the SNR.
