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首页> 外文期刊>The Astrophysical journal >ON THE RAPID SPIN-DOWN AND LOW-LUMINOSITY PULSED EMISSION FROM AE AQUARII
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ON THE RAPID SPIN-DOWN AND LOW-LUMINOSITY PULSED EMISSION FROM AE AQUARII

机译：AE AQUARII的快速自旋和低亮度脉冲发射

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AE Aqr is an unusual close binary system with a very short white dwarf spin period, a high spin-down rate, a relatively low quiescent luminosity, and clear pulse signals. The exact nature of the large spin-down power has not been well explained mainly because the observed luminosities in various energy ranges are much lower than the spin-down power. We consider an unconventional picture of AE Aqr in which an accreting white dwarf, modeled as a magnetic dipole whose axis is misaligned with the spin axis, is rapidly spun down via gravitational radiation emission and therefore the spin-down power is not directly connected to any observable electromagnetic emission. The rapid spin-down is caused by the nonaxisymmetric polar mounds of accreted material slowly spreading away from the magnetic poles over the surface of the star. The effectiveness of the spin-down driven by the gravitational radiation depends on complex diffusion and thermonuclear burning of the accretion mound material. The accretion proceeds at high altitudes toward the magnetic poles of the white dwarf, while a large fraction of the inflowing material is ejected in a propeller-like manner. Based on the observed quiescent X-ray and UV emission, the magnetic field strength is estimated as ～1 x 10~5η_X~(-1/2) G and the mass accretion rate as ～1 x 10~(15)η_X~(-1) g s~(-1), where η_X < 1 is the X-ray radiative efficiency. A large fraction of the accreted mass is flung out by the propeller action, and ～50% of the accreted material arrives at the magnetic poles. The electromagnetic dipole emission is expected at the level of ～1 x 10~(29)η_X~(-1) ergs s~(-1), which suggests that, for η_X ～ 0.1, the observed radio luminosity could be well accounted for by dipole radiation.
机译：AE Aqr是一种不寻常的紧密二进制系统，具有非常短的白矮星自旋周期，高的自旋降速率，相对较低的静态发光度和清晰的脉冲信号。大旋转功率的确切性质尚未得到很好的解释，主要是因为在各种能量范围内观察到的光度远低于旋转功率。我们考虑到AE Aqr的一幅非常规图片，其中一个积聚的白矮星被建模为一个磁偶极子，其轴与自旋轴未对齐，但由于重力辐射而迅速旋转，因此自旋降速功率未直接与任何可观察到的电磁辐射。快速降落是由吸积物质的非轴对称极性土丘从恒星表面的磁极缓慢扩散开来引起的。由重力辐射驱动的旋转下降的有效性取决于吸积土材料的复杂扩散和热核燃烧。吸积物在高空朝白矮星的磁极前进，而大部分流入的物质以螺旋桨状喷出。根据观察到的静态X射线和紫外线发射，磁场强度估计为〜1 x 10〜5η_X〜（-1/2）G，质量增加率约为〜1 x 10〜（15）η_X〜（ -1）gs〜（-1），其中η_X<1是X射线辐射效率。由于螺旋桨的作用，大量的堆积物被甩出，约50％的堆积物到达磁极。电磁偶极子发射预期在〜1 x 10〜（29）η_X〜（-1）ers s〜（-1）的水平，这表明，对于η_X〜0.1，可以很好地解释观测到的无线电发光度。通过偶极子辐射。

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