Time domain astronomy

 Credit: PS1 Science Consortium

Credit: PS1 Science Consortium

 

The dynamic Universe is full of energetic phenomena related to stars that merge, erupt, explode, and become torn apart by black holes. I coordinate multi-wavelength (gamma-ray through radio) observations of these transients after they have been discovered by amateur astronomers and professional sky surveys. Cooperation between the world's leading space- and ground-based facilities is often required, including the Hubble Space Telescope, Jansky Very Large Array, Chandra X-ray Observatory, the Gemini North and South 8.1m telescopes, and the MMT and Magellan 6.5m telescopes.  

 

 

High-energy astrophysics

 Credit: ESO/Wikimedia Commons

Credit: ESO/Wikimedia Commons

 

Core-collapse supernovae are among the most powerful and influential explosions in the universe. They shape galaxies, produce exotic objects such as neutron stars, black holes, and some gamma-ray bursts, are a major site of nucleosynthesis and dust formation, are prodigious emitters of neutrinos, and are likely to be strong Galactic sources of gravitational waves. Understanding the physics behind massive star explosions drives state-of-the-art simulations being run on the world’s most powerful computers. I develop three-dimensional reconstructions of supernova debris fields that uniquely probe the progenitor stars and explosion dynamics of supernovae.

Click here for my web app of the supernova remnant Cassiopeia A.

 

 

Stellar mass loss and evolution

 Credit: ESO/L. Calçada

Credit: ESO/L. Calçada

 

Massive stars can undergo violent eruptive mass loss months to years before core collapse. This phenomenon cannot be adequately explained through modern stellar evolution models and may have serious ramifications in many areas of astronomy that depend on accurate mass loss estimates and detailed knowledge of supernova explosion products. Myself and collaborators are investigating the extent to which eruptive activity may prelude all supernovae, and attempting to understand its various possible origins that may be related to core instabilities and/or interaction with binary companion stars.  

 

 

Dust and molecules

 Credit: ESO / M. Kornmesser

Credit: ESO / M. Kornmesser

 

Supernovae likely play a key role in the production of large quantities of dust that have been observed in high redshift galaxies. However, the efficiency of dust production and the physical properties of the dust grains themselves are not firmly understood. Closely tracking the formation and destruction of dust and molecules around supernovae months after explosion to millennia later in supernova remnants enables us to investigate these important issues in a diverse range of supernova progenitor systems. 

 

 

Solar system dynamics

 Sequence of images showing the discovery of the irregular moon of Uranus named Ferdinand.

Sequence of images showing the discovery of the irregular moon of Uranus named Ferdinand.

 

Beyond the orbit of Neptune lies the Kuiper Belt, which is a vast reservoir of ice cometary material ranging in size from a few meters to hundreds of kilometers. I helped catalogue this region of the solar system and map its structure in an effort to model the formation of the Giant Planets of our solar system. I also contributed to the discovery of irregular moons orbiting the planets Uranus and Neptune. I named one of the Uranian moons Ferdinand