On the nature of long-period dwarf novae with rare and low-amplitude outbursts
On the nature of long-period dwarf novae with rare and low-amplitude outbursts
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罕见低振幅爆发的长周期矮新星的性质
DOI：
10.1093/pasj/psy073
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发表时间：
2018
影响因子：
2.3
通讯作者：
Hiroyuki; et al.
中科院分区：
文献类型：
--
作者：
Kimura;Mariko; Kato;Taichi; Maehara;Hiroyuki; et al.
有几个特殊的长周期矮新星状天体，显示出罕见的低振幅爆发，具有高度电离的发射线; 1 SWASP J162117+441254，BD Pav和V364 Lib就是其中之一。一些研究人员甚至怀疑1 SWASP J1621和V364 Lib是否具有与正常矮新星相同的性质。我们通过我们的光学光度学和光谱学研究了这三个天体的奇特爆发，并对其轨道变化进行了数值模拟，以研究它们的性质。我们发现，它们的爆发持续了很长的时间间隔（几十天），在爆发的早期阶段，通常可以观察到亮度的缓慢上升。我们的分析和数值模拟表明，1 SWASP J1621有一个非常高的倾角，接近90°，加上一个微弱的热点。虽然BD Pav似乎具有稍低的倾斜度（± 75°），但其他属性与1 SWASP J1621中的属性相似。另一方面，V364 Lib似乎有一颗巨大的白色矮星，一颗炽热的伴星星星，以及一个低倾角（约35°）。此外，这三个物体可能具有低转移率和（或）由于轨道周期长而产生的大圆盘。我们发现，这些属性的三个对象可以解释其罕见的和低幅度的爆发的背景下，在正常的矮新星没有强磁场的磁盘不稳定性模型。此外，我们认为在爆发中观测到的高度电离的发射线是由于一个高倾角和/或一个大质量的白色矮星。这类天体的更多实例可能无法识别，因为它们不起眼的爆发很容易被忽视。
There are several peculiar long-period dwarf-nova-like objects that show rare, low-amplitude outbursts with highly ionized emission lines; 1SWASP J162117+441254, BD Pav, and V364 Lib are among them. Some researchers even doubt whether 1SWASP J1621 and V364 Lib have the same nature as normal dwarf novae. We studied the peculiar outbursts in these three objects via our optical photometry and spectroscopy, and performed numerical modeling of their orbital variations to investigate their properties. We found that their outbursts lasted for a long interval (a few tens of days), and that slow rises in brightness were commonly observed during the early stage of their outbursts. Our analyses and numerical modeling suggest that 1SWASP J1621 has a very high inclination, close to 90°, plus a faint hot spot. Although BD Pav seems to have a slightly lower inclination (∼75°), the other properties are similar to those in 1SWASP J1621. On the other hand, V364 Lib appears to have a massive white dwarf, a hot companion star, and a low inclination (∼35°). In addition, these three objects possibly have a low transfer rate and/or large disks originating from the long orbital periods. We found that these properties of the three objects can explain their infrequent and low-amplitude outbursts within the context of the disk instability model in normal dwarf novae without a strong magnetic field. In addition, we suggest that the highly ionized emission lines in outburst are observed due to a high inclination and/or a massive white dwarf. More instances of this class of object may be unrecognized, since their unremarkable outbursts can be easily overlooked.