论文标题
在2019年Nova Scuti的高级Nebular阶段，质量射血发作引起的多种耀斑
Multiple flares caused by mass ejection episodes during the advanced nebular phase of Nova Scuti 2019
论文作者
论文摘要
Our photometric and spectroscopic monitoring shows that starting with 2020 June 4, day +217 from optical maximum and well into its advanced nebular stage, Nova Sct 2019 began displaying a series of nine large amplitude flares (up to Delta(m)~1.7 mag), characterized by a rapid rise to peak (=<10 hours) and a fast exponential decline (e-folding time =<50 hours).耀斑之间的时间间隔三角洲（t）遵循有序的序列，从8.43下降到4.90天，安全地允许排除任何其他耀斑而不会被观测值记录的任何其他耀斑。当耀斑的序列到2020年7月28日（+271天）结束时，Nova SCT 2019降低了其总体下降速度从三角洲（M）= 0.0067 mag/day/Day到0.0027 mag/day/day。耀斑是由远离燃烧的WD以高速（约1000 km/s）排出的物质引起的。在被排出的材料中每种耀斑形成的冷却器伪光层导致重组波通过原始的Nova弹出（在WD的〜170 au）中传播，从[FEX]和[FEVII]淬灭了[FEVII]的发射，并从较低的电离物种中增强。每次耀斑之后，一旦少量被驱逐的材料变成光学薄，原始的Nova弹射器恢复了[FEX]和[FEVII]发射线，这一事实清楚地证明了由燃烧的WD在弹出上施加的直接光电离心动作。虽然另一个已知的耀斑Novae（V458 VUL，V4745 SGR和V5588 SGR）呈现了接近最大亮度的耀斑，并且随着Delta（T）的增加，Nova SCT 2019在先进的Nebular阶段展示它们是独一无二的。
Our photometric and spectroscopic monitoring shows that starting with 2020 June 4, day +217 from optical maximum and well into its advanced nebular stage, Nova Sct 2019 began displaying a series of nine large amplitude flares (up to Delta(m)~1.7 mag), characterized by a rapid rise to peak (=<10 hours) and a fast exponential decline (e-folding time =<50 hours). The time interval Delta(t) between flares follows an ordered sequence, declining from 8.43 to 4.90 days, that safely allows to exclude that any other flare occured without being recorded by the observations. When the sequence of flares was over by 2020 July 28 (day +271), Nova Sct 2019 slowed its overall decline rate from Delta(m)=0.0067 mag/day to 0.0027 mag/day. The flares were caused by material expelled at high velocity (~1000 km/s) from the still burning WD. The cooler pseudo-photosphere forming at each flare in the expelled material, resulted in a recombination wave to spread through the original nova ejecta (at ~170 AU from the WD), quenching emission from [FeX] and [FeVII] and boosting that from lower ionization species. After each flare, once the small amount of expelled material had turned optically thin, the original nova ejecta resumed displaying [FeX] and [FeVII] emission lines, a fact that clearly proves the direct photo-ionization action exerted on the ejecta by the burning WD. While the other known flaring novae (V458 Vul, V4745 Sgr, and V5588 Sgr) presented the flares close to maximum brightness and with increasing Delta(t), Nova Sct 2019 is unique in having displayed them during the advanced nebular stage and with decreasing Delta(t).
