Evolution of helium-accreting carbon-oxygen white dwarfs towards helium-detonations

• Applicant: Professor Dr. Norbert Langer, since 5/2013
• Subject Area: Astrophysics and Astronomy
• Term: from 2013 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 232131047

• Final Report Year: 2019

Final Report Abstract

The purpose of this project was to study the role of both binarity and magnetic torques in binary systems composed of one helium-rich (He) star and a carbon-oxygen (CO) white dwarf (WD) with respect to their ability to produce supernova (SN) explosions via the double detonations scenario. Both of these aspects had received insufficient attention by the astrophysical community at the time of submission of the proposal. The project largely succeeded in its goals, providing valuable contributions to the ongoing discussion on the identity of progenitors of certain types of SN explosions, especially those of Types Ia and Iax. Importantly, it was shown that these types of systems are unlikely progenitors of SNe of Types Ia and Iax via the double detonation scenario, which, up to date, is one of the favored proposed production mechanisms for these transients. The effects of accurate modeling of binarity, and the associated need to take the evolution of the mass donor (i.e. the He star) into account, disfavor the production of helium detonations when compared to (non-physical) accretion at constant accretion rates. Inclusion of rotation and magnetic torques disfavors the production of SNe of Types Ia and Iax due to the implied high amounts of accreted material required in order to induce helium ignition in the quasi-rigidly rotating WD. However, these systems may lead to a number of different transients, ranging from spectrally peculiar SNe to massive helium novae. While these predicted transients still lack a definitive observational counterpart, further study of this type of system is merited.

Publications

• Models for the evolution of close binaries with he-star and white dwarf components towards type ia supernova explosions. A&A, 589:A43, 2016
  P. Neunteufel, S.-C. Yoon, and N. Langer
  
• Helium ignition in rotating magnetized CO white dwarfs leading to fast and faint rather than classical Type Ia supernovae. A&A, 602:A55, February 2017
  P. Neunteufel, S.-C. Yoon, and N. Langer
  
• The Evolution of Helium Star Plus Carbon-Oxygen White Dwarf Binary Systems and Implications for Diverse Stellar Transients and Hypervelocity Stars
  P. Neunteufel, S. C. Yoon, and N. Langer