The effect of a wider initial separation on common envelope binary interaction simulations
De Marco, O
Monthly Notices of the Royal Astronomical Society
Oxford University Press
Copyright © 2016, The Authors
We present hydrodynamic simulations of the common envelope binary interaction between a giant star and a compact companion carried out with the adaptive mesh refinement code ENZO and the smooth particle hydrodynamics code PHANTOM. These simulations mimic the parameters of one of the simulations by Passy et al. but assess the impact of a larger, more realistic initial orbital separation on the simulation outcome. We conclude that for both codes the post-common envelope separation is somewhat larger and the amount of unbound mass slightly greater when the initial separation is wide enough that the giant does not yet overflow or just overflows its Roche lobe. PHANTOM has been adapted to the common envelope problem here for the first time and a full comparison with ENZO is presented, including an investigation of convergence as well as energy and angular momentum conservation. We also set our simulations in the context of past simulations. This comparison reveals that it is the expansion of the giant before rapid in-spiral and not spinning up of the star that causes a larger final separation. We also suggest that the large range in unbound mass for different simulations is difficult to explain and may have something to do with simulations that are not fully converged.
RI is grateful for financial support provided by the International Macquarie University Research Excellence Scholarship. JS acknowledges support from the Australian Research Council Discovery Project (DP12013337) programme and the University of Florida Theoretical Astrophysics Fellowship. ODM gratefully acknowledges support from the Australian Research Council Future Fellowship grant FT120100452. J-CP acknowledges funding from the Alexander von Humboldt Foundation. DP and JW acknowledge funding from ARC Discovery Project DP130102078 and DP via Future Fellowship FT130100034. This research was undertaken, in part, on the National Computational Infrastructure facility in Canberra, Australia, which is supported by the Australian Commonwealth Government, on the swinSTAR supercomputer at Swinburne University of Technology and on the machine Kraken through grant TG-AST130034, a part of the Extreme Science and Engineering Discovery Environment (XSEDE), supported by NSF grant number ACI-1053575. Computations described in this work were performed using the ENZO code (http://enzo-project.org), which is the product of a collaborative effort of scientists at many universities and national laboratories. We are also grateful for extremely helpful comments by the anonymous referee.
This is the final version of the article. Available from Oxford University Press via the DOI in this record.
Vol. 464, pp. 4028 - 4044