The Dynamical Status of Stephan's Quintet
The Dynamical Status of Stephan's Quintet
复制标题
史蒂芬五重奏的动态状况
DOI：
10.1086/310817
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
I. Márquez
中科院分区：
文献类型：
--
作者：
M. Molés;J. Sulentic;I. Márquez;I. Márquez
斯蒂芬五重星系（SQ）的多波长数据与这个紧凑星系群的以下模型一致。(1)不和谐红移星系NGC 7320是一个不相关的前景星系。(2)在过去，SQ是一个包含NGC 7317、7318 A、7319和7320 C的一致红移四重谱。NGC 7320 C在108年前与该星系团发生了几次碰撞（可能不是第一次），并从NGC 7319中剥离了星际介质。(3)在现在的SQ中，又是一个包含NGC 7317、7318 A、B和7319的和谐四重奏。NGC 7318 B现在第一次以高速进入该星系群，形成了一个激波区。如果大多数紧群都像SQ，那么它们经常会被陷入的邻居访问，这些邻居会扰乱群和它们自己。SQ代表了在小群体环境中二次跌倒的强有力证据。潮汐剥离减少了下落星系的质量，从而增加了它们轨道衰变的时间尺度。几乎没有证据表明这些高速“入侵者”会被迅速捕获和/或与系统合并。相反，它们是维持紧密群体免于崩溃的机制。有效的气体剥离可以解释在致密星系群中观察到的低星星形成率，残留气体进入星系核也可能促进活跃星系核活动的开始。
Multiwavelength data for Stephan's Quintet (SQ) are consistent with the following model for this compact galaxy group. (1) Discordant-redshift NGC 7320 is an unrelated foreground galaxy. (2) In the past SQ was an accordant-redshift quartet involving NGC 7317, 7318A, 7319, and 7320C. NGC 7320C collided (probably not for the first time) with the group a few times 108 yr ago and stripped the interstellar medium from NGC 7319. (3) In the present SQ is again an accordant quartet involving NGC 7317, 7318A, B, and 7319. NGC 7318B is now entering the group at high velocity for the first time, giving rise to a shock zone. If most compact groups are like SQ, then they are frequently visited by infalling neighbors that perturb the group and themselves. SQ represents strong evidence for secondary infall in a small group environment. Tidal stripping reduces the mass of the infalling galaxies, thereby increasing the timescale for their orbital decay. There is little evidence that these high-velocity “intruders” are rapidly captured and/or merge with the system. Instead, they are the mechanism that sustains compact groups against collapse. Efficient gas stripping may account for the low star formation rate observed in compact groups, and infall of residual gas into galactic nuclei may also foster the onset of active galactic nucleus activity.