Astronomy & Astrophysics Seminar
Griffin Hosseinzadeh, cfa & Azalee Bostroem, UC davis
Speaker: Griffin Hosseinzadeh
Title: The Mystery of a Supposed Massive Star in a Brightest Cluster Galaxy
Because core-collapse supernovae are the explosions of massive stars, which have relatively short lifetimes, they occur almost exclusively in galaxies with active star formation. On the other hand, the Type Ibn supernova PS1-12sk exploded in an environment that is much more typical of thermonuclear (Type Ia) supernovae: on the outskirts of the brightest elliptical galaxy in a galaxy cluster. The lack of any obvious star formation at that location presented a challenge to models of Type Ibn supernovae as the explosions of very massive Wolf-Rayet stars. I will present a supplementary search for star formation at the site of PS1-12sk, now that the supernova has faded, via deep ultraviolet imaging of the host cluster with the Hubble Space Telescope. We do not detect any UV emission within 1 kpc of the supernova location, which allows us deepen the limit on star formation rate by an order of magnitude compared to the original study on this event. In light of this new limit, I will discuss whether or not the progenitors of Type Ibn supernovae can be massive stars, and what reasonable alternatives have been proposed
Speaker: Azalee Bostroem
Title: What can supernovae tell us about massive stars?
Massive stars, the progenitors of core-collapse supernovae (CCSNe), are not well understood, especially as they near core-collapse. Modeling multi-wavelength observations that span the photometric and spectroscopic evolution of a supernova allows us to describe the progenitor star (e.g. mass, radius, mass-loss history) as well as the explosion parameters (e.g. explosion energy, explosion asymmetry, and nucleosynthesis yields). We will discuss the progenitor models of two CCSNe: ASASSN-15oz and DLT18aq (2018ivc) as well as future work to characterize the progenitors of a sample of CCSNe through light curve and nebular spectra modeling.
Seminar Organizer: Dr. Omer Bromberg