标题： UGC 2773-OT的持续爆发：终于，一个长达十年的河外Eta Carinae相似体 显示英文标题

标题： The Persistent Eruption of UGC~2773-OT: Finally, a Decade-Long Extragalactic Eta Carinae Analog

摘要： 虽然SN假超新星爆发在光谱中显示窄的H线且其峰值绝对星等典型地在-13到-14等之间，与η 大犬座的特大爆发相似，但迄今为止观测到的大多数河外事件在持续时间上与η 大犬座有很大不同。 它们的明亮阶段通常持续100天或更短，而不是持续数年。 暂现源UGC2773-OT的峰值绝对星等与其他SN假超新星类似，但在发现前逐渐上升了5年。 自发现以来的6年里，它以非常缓慢的速度变暗（每年0.26等）。 总体而言，我们认为它的长达十年的爆发迄今为止是已知最接近η 大犬座19世纪爆发的模型。 我们讨论了这次爆发的广泛光谱观测。 光谱显示出有趣的径向速度和谱线形状的变化，我们在细节上进行了讨论，包括一个不对称的Hα发射线，我们证明这与双极星云的喷发一致，可能很像η 大犬座的“小人马座”。 此外，谱线宽度、谱线轮廓、蓝端过量发射（类似于IIn型超新星）以及Hα强度的变化表明，在爆发后期存在强烈的周围星际相互作用。 这支持了η 大犬座爆发的扩展平台可能是由冲击波相互作用提供能量的观点。 然而，一个有趣的不同之处在于，与η 大犬座相比，UGC2773-OT迄今为止尚未表现出与双星近日点事件相关的重复短暂亮度峰值。 显示英文摘要

摘要： While SN impostors resemble the Great Eruption of eta Car in the sense that their spectra show narrow H lines and they have typical peak absolute magnitudes of -13 to -14 mag, most extragalactic events observed so far are quite different from eta Car in duration. Their bright phases typically last for 100~d or less, rather than persisting for several years. The transient object UGC2773-OT had a similar peak absolute magnitude to other SN impostors, but with a gradual 5-yr prediscovery rise. In the 6 yr since discovery, it has faded very slowly (0.26 mag/yr). Overall, we suggest that its decade-long eruption is so far the best known analog of eta Car's 19th century eruption. We discuss extensive spectroscopy of the ongoing eruption. The spectra show interesting changes in velocity and line shape that we discuss in detail, including an asymmetric Halpha emission line that we show is consistent with the ejection of a bipolar nebula that could be very much like the Homunculus of eta Car. Moreover, changes in the line width, line profile, blue excess emission resembling that of Type IIn supernovae, and the intensity of Halpha suggest the presence of strong circumstellar interaction in the eruption at late times. This supports the hypothesis that the extended plateau of eta Car's eruption may have been powered by shock interaction as well. One interesting difference compared to eta Car, however, is that UGC2773-OT so far does not exhibit the repeated brief spikes in luminosity that have been associated with binary periastron events.