A complete light curve of the neglected eclipsing binary Algol V548 Cygni in the UV band was obtained with the Lunar-based Ultraviolet Telescope in 2014 May. Photometric solutions are obtained using the Wilson–Devinney method. It is found that solutions with and without third light are quite different. The mass ratio without third light is determined to be q?=?0.307, while that derived with third light is q?=?0.606. It is shown that V548 Cygni is a semi-detached binary where the secondary component is filling the critical Roche lobe. An analysis of all available eclipse times suggests that there are three cyclic variations in the O–C diagram that are interpreted by the light travel-time effect via the presence of three additional stellar companions. This is in agreement with the presence of a large quantity of third light in the system. The masses of these companions are estimated as m sin i'?~?1.09, 0.20, and 0.52 M⊙. They are orbiting the central binary with orbital periods of about 5.5, 23.3, and 69.9 years, i.e., in 1:4:12 resonance orbit. Their orbital separations are about 4.5, 13.2, and 26.4 au, respectively. Our photometric solutions suggest that they contribute about 32.4% to the total light of the multiple system. No obvious long-term changes in the orbital period were found, indicating that the contributions of the mass transfer and the mass loss due to magnetic braking to the period variations are comparable. The detection of three possible additional stellar components orbiting a typical Algol in a multiple system make V548 Cygni a very interesting binary to study in the future.
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机译：2014年5月，使用基于月球的紫外线望远镜获得了在紫外线波段被忽略的二元Algol V548 Cygni的完整光曲线。使用Wilson-Devinney方法获得光度学解决方案。发现具有和不具有第三光的解决方案是完全不同的。没有第三光的质量比被确定为q≥0.307，而来自第三光的质量比被确定为q≥0.606。结果表明，V548 Cygni是半分离的二进制文件，其中次要成分正在填充关键的罗氏瓣。对所有可用日食时间的分析表明，在O–C图中存在三个周期性变化，这是通过存在三个附加恒星伴星而由光传播时间效应来解释的。这与系统中存在大量的第三光是一致的。这些伴星的质量估计为m sin i'〜1.09、0.20和0.52M⊙。它们以大约5.5年，23.3年和69.9年的轨道周期（即1：4：12共振轨道）在中央双星轨道上运行。它们的轨道间隔分别约为4.5、13.2和26.4 au。我们的光度学解决方案表明，它们对多重系统的总光线贡献约32.4％。在轨道周期中没有发现明显的长期变化，表明质量传递和由于电磁制动引起的质量损失对周期变化的贡献是可比的。在一个多系统中，三个典型的Algol围绕着三个可能的额外恒星成分的检测，使得V548 Cygni成为将来研究的非常有趣的二进制文件。
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