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

吸氦碳氧白矮星向氦爆炸的演化

基本信息

批准号：
232131047
负责人：
Professor Dr. Norbert Langer, since 5/2013
金额：
--
依托单位：
Department of Physics and Astronomy
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/232131047?language=en
关键词：
Evolution helium accreting carbon oxygen

项目摘要

It is believed that thermonuclear explosions in accreting white dwarfs are responsible for many luminous transients in the Universe, including Type Ia supernovae that are important objects for the precision cosmology and for the chemical evolution of the universe. Recently, detonations of the highly degenerate helium shell in a CO white dwarf that slowly accretes helium-rich matter has been proposed as a possible mechanism for Type Ia supernovae as well as for some peculiar Type Ib supernovae. The observable outcomes of a helium detonation sensitively depends on the thermodynamic conditions of the helium shell when it ignites. This project will systematically explore the evolution of helium-accreting CO white dwarfs in close binary systems, to predict which types of explosion would occur via helium detonation in the universe. Following-up our previous studies on the effects of rotation on the evolution of accreting white dwarfs, we will first investigate the effects of magnetic torques due to the so-called Spruit-Tayler dynamo on the evolution of helium-accreting white dwarfs and its implications for supernova explosions induced by helium detonations. Particular attention will be given to the consequences of frictional heating in differentially rotating layers in white dwarfs that are spun-up by mass and angular momentum accretion, and to rotationally induced chemical mixing. Following this, we will calculate self-consistent binary star evolution models to investigate whether time-dependent mass transfer in a close binary system would lead to a merger or significant change of the binary orbit, so as to affect the final fate of the system. With these studies, we will be able to produce realistic progenitor models for helium detonations, and to address the questions whether the majority of ordinary SNe Ia can be produced via helium detonations, which other transients (helium novae, peculiar SNe Ia, or peculiar SNe Ib) would be expected otherwise, and what would be the consequences for nucleosynthesis.

人们相信，在吸积白色矮星的热核爆炸是宇宙中许多发光瞬变的原因，包括Ia型超新星，它们是精确宇宙学和宇宙化学演化的重要对象。最近，CO白色矮星中的高度简并氦壳层的爆炸被认为是Ia型超新星和一些特殊的Ib型超新星的可能机制。氦爆轰的可观测结果敏感地依赖于氦壳层点燃时的热力学条件。该项目将系统地探索密近双星系统中氦吸积CO白色矮星的演化，以预测宇宙中氦爆炸会发生哪种类型的爆炸。继我们以前关于自转对吸积白色矮星演化的影响的研究之后，我们将首先研究由所谓的Spruit-Tayler发电机引起的磁矩对氦吸积白色矮星演化的影响及其对氦爆炸引起的超新星爆炸的影响。特别注意将给予摩擦加热的后果，在不同的旋转层中的白色矮星，旋转的质量和角动量吸积，并旋转诱导的化学混合。在此基础上，我们将计算自洽的双星星星演化模型，以研究在一个紧密的双星系统中，随时间变化的质量转移是否会导致合并或双星轨道的显著变化，从而影响系统的最终命运。通过这些研究，我们将能够产生现实的氦爆轰祖先模型，并解决以下问题：大多数普通超新星Ia是否可以通过氦爆轰产生，其他瞬变（氦新星，特殊超新星Ia或特殊超新星Ib）将被预期，以及核合成的后果。