In a recent study published in Monthly Notices of the Royal Astronomical Society, a research group led by Assistant professor WU Chengyuan from Yunnan Observatories of the Chinese Academy of Sciences investigated the evolution of post-merger remnants resulting from the coalescence of double oxygen-neon white dwarfs. Researchers found that the final fate of such remnants is impacted by the process of convective boundary mixing. However, the wind mass-loss process and rotation may not affect the evolution and final fate of the remnant too much.

Double white dwarfs in binary systems can merger together due to the gravitational wave radiation. Double white dwarf binaries are important gravitational wave sources in our Galaxy, and the massive of which are related to the type Ia supernovae, electron capture supernovae and millisecond pulsars. Thus it is very important to investigate double white dwarf mergers.

At present, the evolutionary outcomes of the mergers of double oxygen-neon white dwarfs are still unclear. Wu constructed the corresponding models to investigate their evolution. Researchers found that such merger remnants can trigger an inwardly propagating O/Ne flame immediately after merger. The remnant will gradually evolve towards giant phase. The evolutionary outcomes are linked to the convective boundary mixing process. If the mixing process cannot impact the flame, the flame will reach the center within 20 years, and the remnant will explode as an iron-core-collapse supernova. On the other hand, if the mixing process can prohibit the flame from reaching the center, the final outcome of the remnant would be an ONeFe WD through electron-capture supernova. Furthermore, researchers found that the wind mass-loss process and rotation may not affect the evolution and final fate of the remnant too much because of the short lifetime of the remnant. This work improves our understanding of the evolution of super-Chandrasekhar mass double ONe white dwarf merger remnants. 

Contact:
WU Chengyuan
Yunnan Observatories, CAS
E-mail: wuchengyuan@ynao.ac.cn