Discovery of a Double-detonation Thermonuclear Supernova Progenitor
Discovery of a Double-detonation Thermonuclear Supernova Progenitor
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DOI：
10.3847/2041-8213/ac48f1
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发表时间：
2021-10
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影响因子：
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通讯作者：
T. Kupfer;E. Bauer;J. van Roestel;E. Bellm;L. Bildsten;J. Fuller;T. Prince;U. Heber;S. Geier-S.-G
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作者：
T. Kupfer;E. Bauer;J. van Roestel;E. Bellm;L. Bildsten;J. Fuller;T. Prince;U. Heber;S. Geier-S.-G
我们发现了一种新的双爆前体系统，该系统由热亚矮星 B (sdB) 双星和白矮星伴星组成，轨道周期 P 球 = 76.34179(2) 分钟。光谱观测结果与氦核燃烧期间位于极端水平分支上的 sdB 恒星一致。嵌合体光变曲线主要由 sdB 星的椭球变形和伴星白矮星的微弱日食所主导。结合光谱和光曲线拟合，我们发现了一颗低质量 sdB 恒星，M sdB = 0.383 ± 0.028 M ⊙ 和一颗大质量白矮星伴星，M WD = 0.725 ± 0.026 M ⊙。从日食中，我们发现白矮星的黑体温度为 26,800 K，导致冷却年龄约为 25 Myr，而我们的 MESA 模型预测 sdB 年龄约为 170 Myr。我们得出的结论是，sdB 首先通过稳定的传质形成，然后是一个共同的包络线，导致约 25 Myr 前白矮星伴星的形成。使用MESA恒星演化代码，我们发现sdB恒星将在约6 Myr内开始质量转移，并在约60 Myr内白矮星的总质量将达到0.92 M ⊙，并具有0.17 M ⊙厚的氦层。这将导致爆炸，很可能会摧毁一颗特殊的热核超新星中的白矮星。 PTF1 J2238+7430只是第二个被确认的双爆热核超新星候选者。使用这两个系统，我们估计至少约 1% 的白矮星热核超新星源自具有厚氦层的 sdB+WD 双星，这与观测到的少量特殊热核爆炸一致。
We present the discovery of a new double-detonation progenitor system consisting of a hot subdwarf B (sdB) binary with a white dwarf companion with a P orb = 76.34179(2) minutes orbital period. Spectroscopic observations are consistent with an sdB star during helium core burning residing on the extreme horizontal branch. Chimera light curves are dominated by ellipsoidal deformation of the sdB star and a weak eclipse of the companion white dwarf. Combining spectroscopic and light curve fits, we find a low-mass sdB star, M sdB = 0.383 ± 0.028 M ⊙ with a massive white dwarf companion, M WD = 0.725 ± 0.026 M ⊙. From the eclipses we find a blackbody temperature for the white dwarf of 26,800 K resulting in a cooling age of ≈25 Myr whereas our MESA model predicts an sdB age of ≈170 Myr. We conclude that the sdB formed first through stable mass transfer followed by a common envelope which led to the formation of the white dwarf companion ≈25 Myr ago. Using the MESA stellar evolutionary code we find that the sdB star will start mass transfer in ≈6 Myr and in ≈60 Myr the white dwarf will reach a total mass of 0.92 M ⊙ with a thick helium layer of 0.17 M ⊙. This will lead to a detonation that will likely destroy the white dwarf in a peculiar thermonuclear supernova. PTF1 J2238+7430 is only the second confirmed candidate for a double-detonation thermonuclear supernova. Using both systems we estimate that at least ≈1% of white dwarf thermonuclear supernovae originate from sdB+WD binaries with thick helium layers, consistent with the small number of observed peculiar thermonuclear explosions.