The Center of Expansion and Age of the Oxygen-rich Supernova Remnant 1E 0102.2-7219

TL;DR

This study measures proper motions of oxygen-rich knots in supernova remnant 1E 0102.2-7219 to determine its expansion center and age, revealing asymmetries likely caused by environmental interactions rather than explosion asymmetry.

Contribution

First precise proper motion measurements of E0102 knots were used to refine its expansion center and age, highlighting environmental effects on remnant expansion.

Findings

Estimated center of expansion with 1.77 arcsecond uncertainty.

Upper limit explosion age of approximately 1738 years.

Detected asymmetries in knot motions linked to environmental interaction.

Abstract

We present new proper motion measurements of optically emitting oxygen-rich knots of supernova remnant 1E 0102.2-7219 (E0102), which are used to estimate the remnant's center of expansion and age. Four epochs of high resolution Hubble Space Telescope images spanning 19 yr were retrieved and analyzed. We found a robust center of expansion of alpha=1:04:02.48 and delta=-72:01:53.92 (J2000) with 1-sigma uncertainty of 1.77 arcseconds using 45 knots from images obtained with the Advanced Camera for Surveys using the F475W filter in 2003 and 2013 having the highest signal-to-noise ratio. We also estimate an upper limit explosion age of 1738 +/- 175 yr by selecting knots with the highest proper motions, that are assumed to be the least decelerated. We find evidence of an asymmetry in the proper motions of the knots as a function of position angle. We conclude that these asymmetries were most likely caused by interaction between E0102's original supernova blast wave and an inhomogeneous surrounding environment, as opposed to intrinsic explosion asymmetry. The observed non-homologous expansion suggests that the use of a free expansion model inaccurately offsets the center of expansion and leads to an overestimated explosion age. We discuss our findings as they compare to previous age and center of expansion estimates of E0102 and their relevance to a recently identified candidate central compact object.