Speaker
Description
Mass loss during the late phases in the lives of massive stars is mostly unknown. Progenitors of stripped-envelope supernovae (SN) experience extensive mass-loss episodes, during which they lose part or all of their hydrogen (H) envelope, and sometimes their helium (He) layer. The loss of the H envelope is generally thought to be caused by interaction with a close binary companion. The stripping mechanism of the He-layer is still unknown.
On rare occasions, these H-poor stars explode during a mass-loss period. When this happens, the material ejected in the explosion collides with the surrounding circumstellar material (CSM), producing observable features caused by the interaction with the CSM. These SNe can be used as probes into the late-stage evolution of these stars.
In this talk, we discuss the mass-loss histories of H-poor interacting SNe. We present our analysis of SN 2021efd, a Type Ib with a remarkable three-peaked light curve, and more recent similar objects. Our analysis suggests that the SN 2021efd exploded whilst losing mass from its He layer. We derive the mass loss rate of 1e-1 to 1e-3 M_sun/yr. We find that the observed interaction features are inconsistent with mass loss driven by stellar winds or binary interaction, and instead point to a series of mass ejections on relatively short timescales, producing clumpy CSM structure around the progenitor.
Finally, we will discuss the implications of these peculiar objects to the evolution of stripped stars, and the prospect of studying objects like these with future large transient surveys such as the Vera Rubin Observatory’s LSST.