第二个螺旋桨的确认：AE ~Aquarii的高倾角双螺旋桨
Confirmation of a Second Propeller: A High-Inclination Twin of AE~Aquarii
摘要：
几十年来，宝瓶座AE（AE Aqr）一直是唯一一颗已知含有磁性推进器的激变变星：一种持续的外流，其从双星系统中的驱逐是由快速旋转的磁化白矮星的自旋下降提供动力的。在2020年，LAMOST-J 024048.51+ 195226. 9（J 0240）被确定为候选食AE Aqr对象，我们提出了三个时期的时间序列光谱，强烈支持这一假设。我们发现，在Thorstensen（2020）（arXiv：2007.09285）记录的光度耀斑期间，Balmer和HeI谱线的零强度半宽通常达到最大值约3000 km/s，远远超过正常激变变星中观测到的值。然而，这与AE Aqr耀斑中看到的高速发射是一致的。此外，我们毫无疑问地确认J 0240是一个深度食系统。闪耀的连续体，HeI和大部分的Balmer发射可能起源于WD附近，因为它们在以次级恒星的下合为中心的日食期间消失。在日食期间，巴尔末辐射的可见部分有一个急剧的减少，它很可能是在延长的外流中产生的。最吸引人的是，这种外流产生了近一半轨道的窄P-Cyg吸收分量，我们证明这种情况与Wynn，King和Horne（1997）预测的外流运动学非常匹配。虽然磁螺旋桨假设的一个重要证据-一个快速的WD旋转周期-仍然难以捉摸，我们的光谱提供了令人信服的支持，存在一个螺旋桨驱动的外流看起来几乎边缘上，使一个新的手段，严格测试理论的螺旋桨现象。
英文摘要：
For decades, AE Aquarii (AE Aqr) has been the only cataclysmic variable star known to contain a magnetic propeller: a persistent outflow whose expulsion from the binary is powered by the spin-down of the rapidly rotating, magnetized white dwarf. In 2020, LAMOST-J024048.51+195226.9 (J0240) was identified as a candidate eclipsing AE Aqr object, and we present three epochs of time-series spectroscopy that strongly support this hypothesis. We show that during the photometric flares noted by Thorstensen (2020) (arXiv:2007.09285), the half-width-at-zero-intensity of the Balmer and HeI lines routinely reaches a maximum of ~3000 km/s, well in excess of what is observed in normal cataclysmic variables. This is, however, consistent with the high-velocity emission seen in flares from AE Aqr. Additionally, we confirm beyond doubt that J0240 is a deeply eclipsing system. The flaring continuum, HeI and much of the Balmer emission likely originate close to the WD because they disappear during the eclipse that is centered on inferior conjunction of the secondary star. The fraction of the Balmer emission remaining visible during eclipse has a steep decrement and it is likely produced in the extended outflow. Most enticingly of all, this outflow produces a narrow P-Cyg absorption component for nearly half of the orbit, and we demonstrate that this scenario closely matches the outflow kinematics predicted by Wynn, King, & Horne (1997). While an important piece of evidence for the magnetic-propeller hypothesis -- a rapid WD spin period -- remains elusive, our spectra provide compelling support for the existence of a propeller-driven outflow viewed nearly edge-on, enabling a new means of rigorously testing theories of the propeller phenomenon.
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