Bow shocks, nova shells, disc winds and tilted discs: the nova-like V341 Ara has it all
Bow shocks, nova shells, disc winds and tilted discs: the nova-like V341 Ara has it all
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DOI：
10.1093/mnras/staa2516
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发表时间：
2020-08
影响因子：
4.8
通讯作者：
N. C. Segura;C. Knigge;J. Acosta-Pulido;D. Altamirano;S. Palacio;J. V. H. Santisteban;M. Pahari
中科院分区：
文献类型：
--
作者：
N. C. Segura;C. Knigge;J. Acosta-Pulido;D. Altamirano;S. Palacio;J. V. H. Santisteban;M. Pahari
V341 Ara 最近被认为是最接近（d ≃ 150 pc）和最亮（V ≃ 10）的类新星灾难变星之一。这个独特的系统被明亮的发射星云包围，很可能是最近新星爆发的残余物。这个星云中嵌入了一个突出的弓形激波，系统的吸积盘风在这里进入它自己的新星外壳。为了确定其基本特性，我们首次对该系统进行了全面的多波长研究。长期光度测量揭示了准周期、超轨道变化，其特征时间尺度为 10-16 天，典型振幅为 ≃1 星等。凌日系外行星勘测卫星（TESS）的高节奏光度测量首次揭示了轨道周期和“负超级驼峰”周期。后者通常被解释为倾斜吸积盘的特征。我们提出了一个最近开发的圆盘不稳定性模型作为对光度行为的合理解释。在我们的光谱数据中，我们清楚地检测到反相吸收和发射线成分。它们的径向速度表明其质量比很高，这反过来又意味着白矮星的质量异常低。我们还根据弓激波中产生的空间分辨 [O iii] 发射来限制系统的风质量损失率；这可用于测试和校准吸积盘风模型。我们认为，V341 Ara 与公元 1240 年中国历史记录中提到的一颗“客星”之间可能存在关联。如果这标志着该系统新星爆发的日期，那么 V341 Ara 将是同类中最古老的被发现的新星，也是测试新星理论的优秀实验室。
V341 Ara was recently recognized as one of the closest (d ≃ 150 pc) and brightest (V ≃ 10) nova-like cataclysmic variables. This unique system is surrounded by a bright emission nebula, likely to be the remnant of a recent nova eruption. Embedded within this nebula is a prominent bow shock, where the system’s accretion disc wind runs into its own nova shell. In order to establish its fundamental properties, we present the first comprehensive multiwavelength study of the system. Long-term photometry reveals quasi-periodic, super-orbital variations with a characteristic time-scale of 10–16 d and typical amplitude of ≃1 mag. High-cadence photometry from theTransiting Exoplanet Survey Satellite (TESS) reveals for the first time both the orbital period and a ‘negative superhump’ period. The latter is usually interpreted as the signature of a tilted accretion disc. We propose a recently developed disc instability model as a plausible explanation for the photometric behaviour. In our spectroscopic data, we clearly detect antiphased absorption and emission-line components. Their radial velocities suggest a high mass ratio, which in turn implies an unusually low white-dwarf mass. We also constrain the wind mass-loss rate of the system from the spatially resolved [O iii] emission produced in the bow shock; this can be used to test and calibrate accretion disc wind models. We suggest a possible association between V341 Ara and a ‘guest star’ mentioned in Chinese historical records in AD 1240. If this marks the date of the system’s nova eruption, V341 Ara would be the oldest recovered nova of its class and an excellent laboratory for testing nova theory.