标题： 一个光谱四合星系作为亚钱德拉塞卡型Ia超新星的可能前身 显示英文标题

标题： A spectroscopic quadruple as a possible progenitor of sub-Chandrasekhar Type Ia supernovae

摘要： 双星系统因其可能作为Ia型超新星（SNIa）爆发的前身天体而受到广泛关注，但紧密三元或四元系统中的长期引力效应也可能在产生SNIa方面发挥关键作用。 这里我们报告在一个星团中发现的一个光谱四重星系（SB4）的性质：2+2等级结构的HD 74438。 它作为疏散星团IC 2391的成员，是迄今为止发现的最年轻的（43 My）SB4，并且是具有最短外部轨道周期的四重系统之一。 外部6年周期的偏心率为0.46，两个内部轨道的周期分别为20.5天和4.4天，偏心率分别为0.36和0.15，它们并不共面。 利用基于地面的高分辨率光谱学与盖亚/依巴谷天文学的创新组合，我们表明该系统正在经历可能提高其中一个内部轨道偏心率的长期相互作用，这高于其分量光谱类型的预期值。 我们计算了HD 74438的未来演化，并表明这个系统是通过白矮星（WD）合并成为次Chandrasekhar质量SNIa的极佳候选者。 考虑到这种特定类型的SNIa的贡献，比仅考虑接近Chandrasekhar质量的SNIa更能解释银河系中铁峰元素的化学演化。 显示英文摘要

摘要： Binaries have received much attention as possible progenitors of Type Ia supernova (SNIa) explosions, but long-term gravitational effects in tight triple or quadruple systems could also play a key role in producing SNIa. Here we report on the properties of a spectroscopic quadruple (SB4) found within a star cluster: the 2+2 hierarchical system HD 74438. Its membership in the open cluster IC 2391 makes it the youngest (43 My) SB4 discovered so far and among the quadruple systems with the shortest outer orbital period. The eccentricity of the 6 y outer period is 0.46 and the two inner orbits, with periods of 20.5 d and 4.4 d, and eccentricities of 0.36 and 0.15, are not coplanar. Using an innovative combination of ground-based high resolution spectroscopy and Gaia/Hipparcos astrometry, we show that this system is undergoing secular interaction that likely pumped the eccentricity of one of the inner orbits higher than expected for the spectral types of its components. We compute the future evolution of HD 74438 and show that this system is an excellent candidate progenitor of sub-Chandrasekhar SNIa through white dwarf (WD) mergers. Taking into account the contribution of this specific type of SNIa better accounts for the chemical evolution of iron-peak elements in the Galaxy than considering only near Chandrasekhar-mass SNIa.