A high resolution HI study towards the supernova remnant Puppis A and its environments

TL;DR

This study uses high-resolution HI observations to refine the systemic velocity and distance of supernova remnant Puppis A, revealing a closer proximity and different environmental interactions than previously thought.

Contribution

It provides a new measurement of Puppis A's systemic velocity and distance using 21 cm line observations, and suggests a relic bubble structure related to its progenitor.

Findings

Systemic velocity constrained between 8 and 12 km/s.

Distance estimated at 1.3 ± 0.3 kpc, closer than previous estimates.

Identification of a possible relic bubble at +8 km/s.

Abstract

We observed the supernova remnant (SNR) Puppis A in the 21 cm line with the Australia Telescope Compact Array with the aim of determining the systemic velocity and, hence, the corresponding kinematic distance. For the compact, background sources in the field, we obtain absorption spectra by applying two methods: (a) subtracting profiles on- and off-source towards continuum emission, and (b) filtering short spacial frequencies in the Fourier plane to remove large scale emission. One of the brightest features to the East of the shell of Puppis A was found to be a background source, probably extragalactic. Removing the contribution from this and the previously known unrelated sources, the systemic velocity of Puppis A turns out to be limited between 8 and 12 km s$^{-1}$, which places this source at a distance of 1.3 $\pm$ 0.3 kpc. From the combined images that include both single dish and interferometric data, we analyze the distribution of the interstellar hydrogen. We suggest that an ellipsoidal ring at $v \sim $+8 km s$^{-1}$ could be the relic of a bubble blown by the progenitor of Puppis A, provided the distance is $\lesssim$ 1.2 kpc. The main consequences of the new systemic velocity and distance as compared with previous publications ($v =$ +16 km s$^{-1}$ and $d = $2.2 kpc) are the absence of a dense interacting cloud to the East to explain the morphology, and the decrease of the shell size and the neutron star velocity, which are now in better agreement with statistical values.