A possible surviving companion of the SN Ia in the Galactic SNR G272.2-3.2

TL;DR

This study investigates the potential surviving companion of a Type Ia supernova in the Galactic SNR G272.2-3.2 using Gaia data, identifying a candidate star with peculiar kinematics and trajectory consistent with the supernova event.

Contribution

The paper presents the first candidate surviving companion for SNR G272.2-3.2, supporting a single-degenerate supernova scenario with an M-type dwarf star.

Findings

Identified a kinematically peculiar star consistent with the supernova remnant center.

Ruled out several other companion types and hypervelocity stars.

Supports the single-degenerate progenitor model for this SNR.

Abstract

We use the {\it Gaia} EDR3 to explore the Galactic supernova remnant SNR G272.2-3.2, produced by the explosion of a Type Ia supernova (SNIa), about 7,500 years ago, to search for a surviving companion. From the abundances in the SNR ejecta, G272.2-3.2 is a normal SN Ia. The {\it Gaia} parallaxes allow to select the stars located within the estimated distance range of the SNR, and the {\it Gaia} proper motions to study their kinematics. From the {\it Gaia} EDR3 photometry, we construct the HR diagram of the selected sample, which we compare with the theoretical predictions for the evolution of possible star companions of SNIa. We can discard several proposed types of companions by combining kinematics and photometry. We can also discard hypervelocity stars. We focus our study on the kinematically most peculiar star, {\it Gaia} EDR3 5323900215411075328 (hereafter MV-G272), a 8.9 $\sigma$ outlier in proper motion. It is of M1-M2 stellar type. Its trajectory on the sky locates it at the center of the SNR, 6,000--8,000 years ago, a unique characteristic among the the sample. Spectra allow a stellar parameters determination and a chemical abundance analysis. In conclusion, we have a candidate to be the surviving companion of the SN Ia that resulted in SNR G272.2-3.2. It is supported by its kinematical characteristics and its trajectory within the SNR. This opens the possibility of a single-degenerate scenario for a SN Ia with an M-type dwarf companion.