Our research focuses on the evolution, death, and afterlife of "massive stars" (≥ 7M_o). These are most often born with companion star(s) orbiting them so close that, as the stars evolve and grow bigger, they "run into each other". This means that there will be a phase of mass transfer that modifies both stars before they end their life in a spectacular supernova – and/or collapse into black holes. The mass transfer phase can often result in a stellar merger, producing unique stellar structures.

At the death of the first star, typically binary systems break apart, shooting out the "widowed" companion(s). These become single stars, but they still carry the signatures of the previous interactions with its now dead former companion. In rare cases, the binary survives, and as the companion catches up with its evolution, further mass-transfer phases can occur, and eventually a small minority ends up as double compact objects (neutron stars or black holes), which spiral inwards due gravitational waves until the present day or until they merge producing a detectable gravitational wave burst.

We are broadly interested in all these phenomena and anything related, but we don't let our main expertise limit our curiosity!

We are also part of the "Theoretical Astrophysics Program (TAP)" at the University of Arizona, which connects the Department of Astronomy, the Department of Physics, and the Lunar and Planetary Lab.

• Aldana Grichener (Steward Theory Fellow)
• Koushik Sen