Core-collapse supernovae, the end-of-life explosions of stars much more massive than the sun, are one of the primary drivers responsible for enriching our solar system and others with all elements heavier than hydrogen and helium. To understand this process of chemical enrichment in the universe, it is critical to understand the diversity of stellar explosions that produce these elements and how they relate to the populations of stars in galaxies.
Roughly one out of four of these exploding stars undergo radical mass loss during their lives, losing their entire outer hydrogen and helium layers before explosion (Type Ibc supernovae). In 2012, I completed a campaign to characterize the host galaxies of 60 of these stripped-envelope core-collapse supernovae. Through modeling of the optical spectra of these host environments, we showed that the level of stripping on the progenitor star (Type Ib or Ic) does not depend measurably on its chemical composition (metallicity; see plot at right). This result limits the role that chemical composition, and metal line-driven stellar winds, can play in the stripping of these massive stars.
Gamma-ray bursts (GRBs) are the most energetic transient events observed in the universe and, because they can be seen at great distances, may become invaluable tracers of star formation in the early universe. A clear association exists between some nearby long GRBs and broad-lined Type Ic supernovae. However, it is not yet understood what causes only a special few of this class of supernovae to produce visible GRBs. We investigate the properties of these supernovae, and especially the environments in which they occur, to look for clues that would explain the physical processes that produce them.
We perform multi-wavelength follow-up observations of new SNe discovered by the high-cadence, multi-band medium-deep survey of the Pan-STARRS1 telescope. You can read more about our study of SN 2010ay here.