标题： 大麦哲伦云中的氦新星——微弱的超软X射线源 [HP99]159 显示英文标题

标题： A helium nova in the Large Magellanic Cloud -- the faint supersoft X-ray source [HP99]159

摘要： 我们提出了一个针对大麦哲伦云（LMC）超软X射线源（SSS）[HP99]159的氦 nova 模型。这个天体已经被检测到作为微弱且持续的SSS约30年，并且最近被解释为稳定氦壳燃烧的来源，因为没有观测到氢谱线。我们发现这个天体也可以被解释为处于氦 nova 衰减阶段。氦 nova 正缓慢衰减至宁静阶段，在此期间观测到的温度、光度和SSS寿命（$\gtrsim 30$年）与质量为$\sim$1.2$M_\odot$的白矮星模型一致。如果是这样的话，这是银河系中V445 Pup之后第二次发现的氦 nova 爆发，也是LMC中首次确认的氦 nova。我们还讨论了伴星氦星的性质以及其与Ia型超新星前身的关系。 显示英文摘要

摘要： We propose a helium nova model for the Large Magellanic Cloud (LMC) supersoft X-ray source (SSS) [HP99]159. This object has long been detected as a faint and persistent SSS for about 30 years, and recently been interpreted to be a source of steady helium-shell burning, because no hydrogen lines are observed. We find that the object can also be interpreted as in a decaying phase of a helium nova. The helium nova is slowly decaying toward the quiescent phase, during which the observed temperature, luminosity, and SSS lifetime ($\gtrsim 30$ years) are consistent with a massive white dwarf model of $\sim$ 1.2 $M_\odot$. If it is the case, this is the second discovery of a helium nova outburst after V445 Pup in our Galaxy and also the first identified helium nova in the LMC. We also discuss the nature of the companion helium star in relation to Type Ia supernova progenitors.