The last breaths of massive stars: constructing the mass-loss history for core-collapse supernovae progenitors
Speaker: Samaporn Tinyanont (National Astronomical Research Institute of Thailand)
Abstract:
Mass loss is central to the evolution of massive stars, dictating their final structure and circumstellar environment at death; thus, responsible for the observed diversity in core-collapse supernovae (CCSNe). Multiple mechanisms are at play, from stellar wind, binary interaction, and eruptions. Observing the SN shock and light interact with circumstellar medium (CSM) can help us reconstruct the mass loss history and constrain the relative contributions from these mechanisms. However, only a small fraction of CCSNe have CSM with appropriate distance and density to produce prolonged strong and easily observable shock interactions. The most close-in CSM ejected years to decades before death, likely associated with late-stage nuclear burning instabilities, produces brief interactions lasting only hours to a few days. I will discuss rapid robotic spectroscopy of young CCSNe to be enabled with the Dual-beam Automatic Rapid Transient Spectrographs (DARTS) currently being built in Thailand to be deployed at the 2.4-meter telescope at Lick Observatory, California. CSM ejected on longer timescales expands far away from the SN and may not cause strong interactions. I will discuss using near-infrared (IR) imaging to catch emerging IR echoes from this type of CSM, measuring its geometry and constraining the mass loss mechanism, highlighting recent observations of SN 2024aecx as a test case. Finally, CSM created by binary Roche-lobe overflow will be dispersed by the time of SN, 105-6 yr later; it can only be observed in Galactic massive stars recently undergone binary interaction. I will discuss the recent radial velocity measurements showing that the peculiar obscured NaSt1 system is likely a massive binary post Roche-lobe overflow. I will also discuss the prospects of finding other systems like it in the Milky Way. Together, these observations construct a complete picture of massive stellar mass loss from Myr to just before death.