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arXiv 1003.0771astro-ph.CO
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非常贫金属的星系:九个天体的电离气体运动学

Very metal-poor galaxies: ionized gas kinematics in nine objects

A. V. Moiseev, S. A. Pustilnik, A. Y. Kniazev

摘要:

利用SAO 6-m望远镜上的扫描法布里-珀罗干涉仪对9个异常缺金属星系的电离气体形态和运动学进行了研究。其中一些非常罕见的天体(目前已知的O/H范围为7.12 < 12+log(O/H)< 7.65,或Zo/35 < Z < Zo/10)被认为是高红移宇宙中“年轻”低质量星系的最佳代表。本研究的主要目标之一是寻找由外部扰动引起的恒星形成(SF)活动的可能证据。最近的结果HI映射的一个小的子样本的XMD恒星形成星系的相互作用引起的SF的重要作用提供了可靠的证据。我们的观测提供了补充或新的信息,即绝大多数研究的XMD矮星具有强烈的扰动气体形态和运动学或存在分离的组件。我们近似观察到的速度场的旋转倾斜薄盘,这使我们能够强大的非圆形气体运动的检测的简单模型。这些数据,反过来,表明当前/最近的相互作用和合并中观察到的增强恒星形成的重要作用。作为我们观测的副产品,我们获得了两个LSB矮星系的数据:Anon J 012544 +075957是合并系统UGC 993的伴星,SAO 0822+3545显示出偏离中心,不对称,低SFR的恒星形成区域,可能是由与伴星XMD矮星系HS 0822+3542的相互作用引起的。

英文摘要:

The study of ionized gas morphology and kinematics in nine eXtremely Metal-Deficient (XMD) galaxies with the scanning Fabry-Perot interferometer on the SAO 6-m telescope is presented. Some of these very rare objects (with currently known range of O/H of 7.12 < 12+log(O/H) < 7.65, or Zo/35 < Z < Zo/10) are believed to be the best proxies of `young' low-mass galaxies in the high-redshift Universe. One of the main goals of this study is to look for possible evidence of star formation (SF) activity induced by external perturbations. Recent results from HI mapping of a small subsample of XMD star-forming galaxies provided confident evidence for the important role of interaction-induced SF. Our observations provide complementary or new information that the great majority of the studied XMD dwarfs have strongly disturbed gas morphology and kinematics or the presence of detached components. We approximate the observed velocity fields by simple models of a rotating tilted thin disc, which allow us the robust detection of non-circular gas motions. These data, in turn, indicate the important role of current/recent interactions and mergers in the observed enhanced star formation. As a by-product of our observations, we obtained data for two LSB dwarf galaxies: Anon J012544+075957 that is a companion of the merger system UGC 993, and SAO 0822+3545 which shows off-centre, asymmetric, low SFR star-forming regions, likely induced by the interaction with the companion XMD dwarf HS 0822+3542.

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