标题： A0620-00再次研究：一个黑洞暂现源案例研究 显示英文标题

标题： A0620-00 revisited: a black-hole transient case-study

摘要： 我们首次对著名黑洞暂现源A0620-00（Nova Mon 1975，V616 Mon）1975/1976爆发的X射线、光学和红外光变曲线进行了详细研究。在爆发的不同阶段，X射线比光学滞后约5至20天。此外，与次级最大值相关的活动在红外波段更早开始。这表明大部分爆发过程发生在吸积盘的外层区域。我们还发现X射线强度有各种下降（持续时间约为1天或更长）。在其中一个下降附近出现了一个光学光变曲线的局部最大值。这个最大值出现在次级最大值后约30天，即接近受照射盘的粘滞时间尺度。我们认为这个特征是次级最大值的“回声”。在爆发结束时，类似的光学局部最大值也会出现，这可能是三级最大值的“回声”。我们发现，在三级最大值附近的光学和X射线下降现象也出现在其他SXTs中。它们总是发生在爆发开始后约150天。我们首次发现A0620-00的X射线谱在爆发开始后约100至150天开始变硬，类似于GS2000+25和GS1124-68。这表明我们在那时见证了所谓的高态向低态的过渡。我们显示A0620-00的光学爆发光变曲线与灾变变星AL Com非常相似。这加强了SXTs和TOADs（或WZ Sge星）性质的相似性，并表明这两组的光学爆发光变曲线由吸积盘特性决定，而不是由致密天体决定。由于照射提供了一种自然机制来延长SXTs的爆发，我们认为这可能在TOAD爆发期间也起作用。 显示英文摘要

摘要： For the first time we have performed a detailed study of the X-ray, optical and infra-red light curves of the 1975/1976 outburst of the famous black-hole transient A0620-00 (Nova Mon 1975, V616 Mon). During the various stages of its outburst the X-rays lag the optical by ~5-20 days. Moreover, the activity associated with the secondary maximum started even earlier in the infra-red. This suggests that most of the outburst processes occur in the outer parts of the disk. We also find various drops in the X-ray intensity (lasting ~1 day or more). Near one of these a local maximum in the optical light curve occurs. This maximum appears ~30 days after the secondary maximum, i.e. close to the viscous time scale of an irradiated disk. We suggest this feature to be an `echo' of the secondary maximum. At the end of the outburst a similar local optical maximum occurs, which might be an `echo' of the tertiary maximum. We find that the drops in the optical and X-rays near the tertiary maximum are also present in other SXTs. They always occur ~150 days after the start of the outburst. We find for the first time that the X-ray spectrum of A0620-00 starts to harden ~100-150 days after the start of its outburst, similar to GS2000+25 and GS1124-68. This suggests we witness the transition from the so-called high to low state at that time. We show that the optical outburst light curve of A0620-00 closely resembles that of the cataclysmic variable AL Com. This strengthens the similarity in the properties of the SXTs and TOADs (or WZ Sge stars), and shows that the optical outburst light curves of both groups are governed by the disk properties and not by the compact object. Since irradiation provides a natural mechanism to prolong the outburst of SXTs, we suggest this could be of influence as well during TOAD outbursts.