The Expansion of the Young Supernova Remnant 0509-68.7 (N103B)

TL;DR

This study measures the expansion of the young Type Ia supernova remnant N103B in the LMC over 17.4 years, estimating an average velocity of 4170 km/s, supporting its classification as a young remnant.

Contribution

First measurement of N103B's expansion velocity using Chandra data over a long baseline, providing insights into its age and dynamics.

Findings

Expansion velocity of 4170 km/s estimated

Remnant's age approximately 850 years

Asymmetrical expansion likely due to circumstellar material

Abstract

We present a second epoch of {\it Chandra} observations of the Type Ia LMC SNR 0509-68.7 (N103B) obtained in 2017. When combined with the earlier observations from 1999, we have a 17.4-year baseline with which we can search for evidence of the remnant's expansion. Although the lack of strong point source detections makes absolute image alignment at the necessary accuracy impossible, we can measure the change in the diameter and the area of the remnant, and find that it has expanded by an average velocity of 4170 (2860, 5450) km s$^{-1}$. This supports the picture of this being a young remnant; this expansion velocity corresponds to an undecelerated age of 850 yr, making the real age somewhat younger, consistent with results from light echo studies. Previous infrared observations have revealed high densities in the western half of the remnant, likely from circumstellar material, so it is likely that the real expansion velocity is lower on that side of the remnant and higher on the eastern side. A similar scenario is seen in Kepler's SNR. N103B joins the rare class of Magellanic Cloud SNRs with measured proper motions.