Discovery of an OB Runaway Star Inside SNR S147

TL;DR

This study identifies a runaway OB star inside SNR S147, linking it to the supernova event and providing insights into the progenitor system and binary interactions prior to the supernova explosion.

Contribution

First detection of an OB runaway star inside an SNR, linking it to the supernova progenitor and analyzing its binary history.

Findings

HD 37424 is a B0.5V runaway star with 74 km/s velocity.

The star was at the supernova site 30 kyr ago, linked to the pulsar PSR J0538+2817.

The SNR is approximately 1333 pc away with an age of 30 kyr.

Abstract

We present first results of a long term study: Searching for OB--type runaway stars inside supernova remnants (SNRs). We identified spectral types and measured radial velocities (RV) by optical spectroscopic observations and we found an early type runaway star inside SNR S147. HD 37424 is a B0.5V type star with a peculiar velocity of 74$\pm$8 km s$^{-1}$. Tracing back the past trajectories via Monte Carlo simulations, we found that HD 37424 was located at the same position as the central compact object, PSR J0538+2817, $30\!\pm\!4$ kyr ago. This position is only $\sim$4 arcmin away from the geometrical center of the SNR. So, we suggest that HD 37424 was the pre--supernova binary companion to the progenitor of the pulsar and the SNR. We found a distance of 1333$^{+103}_{-112}$ pc to the SNR. The zero age main sequence progenitor mass should be greater than 13 $M_\odot$. The age is $30\pm4$ kyr and the total visual absorption towards the center is 1.28$\pm$0.06 mag. For different progenitor masses, we calculated the pre--supernova binary parameters. The Roche Lobe radii suggest that it was an interacting binary in the late stages of the progenitor.