Ongoing Gas Stripping in the Virgo Cluster Spiral Galaxy NGC 4522
Ongoing Gas Stripping in the Virgo Cluster Spiral Galaxy NGC 4522
复制标题
处女座星团螺旋星系 NGC 4522 中正在进行的气体剥离
DOI：
10.1086/300683
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
R. Koopmann
中科院分区：
文献类型：
--
作者：
J. Kenney;R. Koopmann
室女座星系团星系NGC 4522是一个最好的螺旋候选人内星系团中星际介质（ICM-ISM）剥离的行动。利用WIYN望远镜拍摄的该大倾角星系的光学宽带和Hα图像揭示了一个相对未受扰动的恒星盘和一个特殊的Hα辐射分布。10%的Hα辐射来自面外H II区，这些区域位于盘一侧上方≥3 kpc长的沉积结构内。这些细丝从明亮的Hα辐射盘的外缘出现，该辐射盘在0.35R25之后突然被截断。截断的Hα盘和平面外的Hα细丝一起使人联想到弓形激波的形态，这强烈表明NGC 4522的ISM正在被ICM的气体压力剥离。相对于室女座星系团的平均速度，该星系的视线速度为1300 km s-1，因此预计会与团内气体发生强烈的相互作用。H II区的存在显然位于盘平面上方，这表明星星的形成发生在剥离的气体中，新形成的恒星将进入星系晕和/或团内空间。在盘中没有H II区域超过0.35R25，并且在剥离的气体中存在H II区域，这表明即使是分子气体也已被有效地从星系盘中移除。
The Virgo Cluster galaxy NGC 4522 is one of the best spiral candidates for intracluster medium–interstellar medium (ICM-ISM) stripping in action. Optical broadband and Hα images from the WIYN telescope of the highly inclined galaxy reveal a relatively undisturbed stellar disk and a peculiar distribution of Hα emission. Ten percent of the Hα emission arises from extraplanar H II regions which appear to lie within filamentary structures ≥3 kpc long above one side of the disk. The filaments emerge from the outer edge of a disk of bright Hα emission which is abruptly truncated beyond 0.35R25. Together the truncated Hα disk and extraplanar Hα filaments are reminiscent of a bow shock morphology, which strongly suggests that ISM of NGC 4522 is being stripped by the gas pressure of the ICM. The galaxy has a line-of-sight velocity of ≃1300 km s-1 with respect to the mean Virgo Cluster velocity and thus is expected to experience a strong interaction with the intracluster gas. The existence of H II regions apparently located above the disk plane suggests that star formation is occurring in the stripped gas, and that newly formed stars will enter the galaxy halo and/or intracluster space. The absence of H II regions in the disk beyond 0.35R25 and the existence of H II regions in the stripped gas suggest that even molecular gas has been effectively removed from the disk of the galaxy.