A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary

TL;DR

This paper reports the discovery of a fast, low-mass supernova, providing direct evidence for ultra-stripped supernovae that lead to the formation of neutron star binaries, a process previously unobserved.

Contribution

It presents the first direct observation of an ultra-stripped supernova, revealing details about its low ejecta mass and explosion characteristics, supporting models of neutron star binary formation.

Findings

Fast-evolving light curve indicating low ejecta mass

Evidence of shock cooling from an extended He-rich envelope

Supports ultra-stripped supernovae as a formation channel for neutron star binaries

Abstract

Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a Type Ic supernova with a fast evolving light curve indicating an extremely low ejecta mass ($\approx 0.2$ solar masses) and low kinetic energy ($\approx 2 \times 10^{50}$ ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended He-rich envelope, likely ejected in an intense pre-explosion mass loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.