Hubble Fellows Symposium

I’m in Baltimore, MD at the Space Telescope Science Institute for the 2017 Hubble Fellows Symposium. I’m giving a talk entitled The evolution and fate of super-Chandrasekhar mass white dwarf merger remnants.

The Evolution and Fate of Super-Chandrasekhar Mass White Dwarf Merger Remnants

Monthly Notices of the Royal Astronomical Society, Volume 463, Issue 4, p.3461-3475

Josiah Schwab, Eliot Quataert, Daniel Kasen

We present stellar evolution calculations of the remnant of the merger of two carbon-oxygen white dwarfs (CO WDs). We focus on cases that have a total mass in excess of the Chandrasekhar mass. After the merger, the remnant manifests as an $L \sim 3\times 10^4 L_\odot$ source for $\sim 10^4$ yr. A dusty wind may develop, leading these sources to be self-obscured and to appear similar to extreme AGB stars. Roughly $\sim 10$ such objects should exist in the Milky Way and M31 at any time. As found in previous work, off-center carbon fusion is ignited within the merger remnant and propagates inward via a carbon flame, converting the WD to an oxygen-neon (ONe) composition. By following the evolution for longer than previous calculations, we demonstrate that after carbon-burning reaches the center, neutrino-cooled Kelvin-Helmholtz contraction leads to off-center neon ignition in remnants with masses $\ge 1.35 M_\odot$. The resulting neon-oxygen flame converts the core to a silicon WD. Thus, super-Chandrasekhar WD merger remnants do not undergo electron-capture induced collapse as traditionally assumed. Instead, if the remnant mass remains above the Chandrasekhar mass, we expect that it will form a low-mass iron core and collapse to form a neutron star. Remnants that lose sufficient mass will end up as massive, isolated ONe or Si WDs.

Started at UC Santa Cruz

I’ve started as a Hubble Fellow in the Department of Astronomy and Astrophysics at UC Santa Cruz. My office is ISB 363.

MESA Summer School 2016

I’m in Santa Barbara, CA at the MESA Summer School. I’m lecturing on how to use MESA’s run_star_extras.f functionality.

20th European Workshop on White Dwarfs

I’m in Coventry, UK at the University of Warwick for the 20th European Workshop on White Dwarfs. I’m giving a talk entitled The evolution and fate of super-Chandrasekhar mass white dwarf merger remnants and presenting a poster entitled Turbulent Chemical Diffusion in Convectively Bounded Carbon Flames.