To appear in the Victor Ambartsumian Centennial Volume " Evolution of Cosmic Objects through their Physical Activity "
To appear in the Victor Ambartsumian Centennial Volume " Evolution of Cosmic Objects through their Physical Activity "
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发表时间：
2010
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通讯作者：
B. Reipurth;C. Aspin
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作者：
B. Reipurth;C. Aspin
ambarsumian是最早认识到FUors的重要性和独特性的研究人员之一，他为猎户座FU类型的罕见爆发源创造了这个术语。在过去的近40年里，大量的观测数据和伴随的理论工作提高了我们对福尔斯的理解。这些结果在这篇简短的综述中进行了总结，特别强调了与FUors二值性有关的观测结果。有人认为，至少有一些FUors代表了年轻的双星从宽星系到近星系的转变，因此是光谱双星形成的标志。EXor现象以及其他各种喷发事件也进行了讨论。最后，我们详细讨论了最近对猎户座V1647的观测，这是在恒星形成区观测到的最近一次喷发。1. 1936年，位于猎户座λ区小黑云B35中的暗淡不规则变星猎户座FU（图1）经历了一次大爆发，在半年的时间里亮度增加了约6等（Wachmann 1954, Herbig 1966）。1969年，另一颗微弱的恒星，位于天鹅座ngc7000区域的LkHα 190 = V1057 Cyg，在一年的时间里也同样变亮了大约5等（Welin 1971）。后者在爆发前后的光谱显示，在蓝色光谱区从T型金牛座发射光谱转变为a型光谱，在红色光谱区转变为F-G0，在Hα线和钠线有明显的Cygni P谱线，并有强烈的锂谱线（Herbig & Harlan 1971）。以上简短的叙述基本上总结了到1971年Victor Ambartsumian发表了一篇关于这两种喷发变量的论文（Ambartsumian 1971）时所能获得的极其有限的信息。在那篇论文中，ambarsumian创造了FUor这个术语，从此这类爆发变量的成员就被人们所知。考虑到当时观测资料的缺乏，毫不奇怪，鉴于我们后来对福尔斯的了解，ambarsumian关于这些喷发的能量来源的想法不再具有相关性。然而，ambarsumian提出了一个普遍且非常重要的观点：对这些现象的研究不应该在观测数据的分析中被忽视，这些现象很少出现，很容易被淹没在一堆表面上相似的事实中，并且在表面的检查中显得不重要。此外，它们极不常见可能是出现在维克多·安巴苏米亚百周年卷《宇宙物体通过其物理活动的演化》中错误倾向的原因。Hayk Harutyunyan， Areg Mickaelian和Yervant Terzian， Gitutyun出版社，埃里温；
Ambartsumian was among the first researchers who recognized the importance and uniqueness of FUors, the term he coined for the rare outburst sources of the FU Orionis type. A wealth of observational data and concomitant theoretical work has advanced our understanding of FUors in the intervening almost 40 years. These results are summarized in this brief review, with special emphasis on observations related to the binarity of FUors. It is argued that at least some FUors represent the transitions of young binaries from a wide to a close system, and are thus signposts of the formation of a spectroscopic binary. The EXor phenomenon is also discussed, together with a variety of other eruptive events. Finally, we discuss in some detail recent observations of V1647 Ori, the latest eruption to have been witnessed in a star forming region. 1. Ambartsumian and the FUors In 1936 the faint irregular variable star FU Orionis, located in the small dark cloud B35 in the λ Orionis region (Fig. 1), underwent a major eruption, increasing in brightness by about 6 magnitudes over a period of half a year (Wachmann 1954, Herbig 1966). In 1969 another faint star, LkHα 190 = V1057 Cyg, located in the NGC 7000 region in Cygnus, similarly brightened by about 5 magnitudes over the span of one year (Welin 1971). Spectra of the latter object before and after the eruption indicated a significant transformation from a T Tauri-type emission spectrum to that of an A-type spectrum in the blue spectral region and F-G0 in the red spectral range, with significant P Cygni profiles at the Hα and sodium lines, and with a strong lithium line (Herbig & Harlan 1971). The above brief account basically summarizes the extremely limited information available on these two eruptive variables by 1971, when Victor Ambartsumian published a paper on the phenomenon (Ambartsumian 1971). In that paper, Ambartsumian coined the term FUor, by which the members of this class of eruptive variables have been known since. Given the dearth of observations available at the time, it is not surprising that Ambartsumian’s ideas of the energy source for these eruptions no longer have relevance in light of all we have subsequently learned about FUors. However, Ambartsumian raised a general and very important point as follows: The study of such phenomena that appear so infrequent, that get lost so easily among a welter of superficially similar facts, and that appear to be unsubstantial in a superficial examination, should not be neglected in an analysis of the observational data. Furthermore, their great infrequency may be responsible for an erroneous tendency 1 To appear in the Victor Ambartsumian Centennial Volume "Evolution of Cosmic Objects through their Physical Activity", eds. Hayk Harutyunyan, Areg Mickaelian and Yervant Terzian, Gitutyun Publishing House, Yerevan,