SDSS J080710+485259 is the longest-period outbursting ultracompact white dwarf binary. Its first-ever detected superoutburst started in 2018 November and lasted for a year, the longest detected so far for any short orbital period accreting white dwarf. Here we show the superoutburst duration of SDSS J080710+485259 exceeds the ∼2 month viscous time of its accretion disk by a factor of about 5. Consequently it follows that neither the empirical relation nor the theoretical relation between the orbital period and the superoutburst duration for AM CVn systems. Six months after the end of the superoutburst the binary remained 0.4 mag brighter than its quiescent level before the superoutburst. We detect a variable X-ray behavior during the post-outburst cooling phase, demonstrating changes in the mass accretion rate. We discuss how irradiation of the donor star, a scenario poorly explored so far and that ultimately can have important consequences for AM CVns as gravitational-wave sour...

中文翻译：

---

来自超紧凑型白矮星的长达一年的超级爆发揭示了施主星辐照的重要性

SDSS J080710 + 485259是最长周期的超紧凑白矮星二进制。它的有史以来第一次探测到的超爆发始于2018年11月，持续了一年，这是迄今为止在所有短轨道上发现白矮星的时间最长的一次。在这里，我们显示SDSS J080710 + 485259的超爆发持续时间超过其吸积盘的约2个月粘性时间约5倍。因此，得出的结论是，轨道周期与超爆发持续时间之间的经验关系和理论关系均无AM CVn系统。超级爆发结束六个月后，二元星体比超级爆发之前的静止水平亮了0.4磁倍。我们在爆发后的冷却阶段检测到了可变的X射线行为，表明了质量累积率的变化。