M83内部区域的运动学与建模
Kinematics and Modeling of the Inner Region of M83
摘要：
利用Gemini South望远镜的三维近红外光谱，获得了M83（NGC 5236）中心区的二维运动学数据。由积分场单元（~5”x 13”或~90 x 240 pc）覆盖的空间区域大致以凸起等照度线的中心为中心，并朝向SE-NW。在半弧秒分辨率下的Pa_beta辐射清晰地显示了围绕三个中心的蜘蛛状图，表明存在扩展质量，我们用Satoh分布描述了扩展质量。其中一个质量浓度被确定为光学核（ON），另一个作为凸起等照度线的中心，类似于CO运动学中心（KC），第三个作为隐藏在光学波长（HN）处的凝结，与10微米发射中的最大波瓣一致。我们运行的数值模拟，考虑到ON，KC和HN和四个以上的集群，代表恒星形成弧在西南部的光学核。我们发现，ON，KC和HN遭受强烈的蒸发和合并在10-50万年。恒星形成弧分散在不到一个轨道周期内，也落入中心。模拟还表明，潮汐条纹提高外壳的冷凝到他们的逃逸速度。这一事实可能会导致在空间分辨率小于凝聚体表观尺寸的运动学观测中高估凝聚体的质量。此外，不同作者声称的包含HII区链的两个ILR共振的存在可能不存在，这是由于不同组分的质量相似以及M83中心300 pc的快速动力学演化。
英文摘要：
Two-dimensional kinematics of the central region of M 83 (NGC 5236) were obtained through three-dimensional NIR spectroscopy with Gemini South telescope. The spatial region covered by the integral field unit (~5" x 13" or ~90 x 240 pc), was centered approximately at the center of the bulge isophotes and oriented SE-NW. The Pa_beta emission at half arcsecond resolution clearly reveals spider-like diagrams around three centers, indicating the presence of extended masses, which we describe in terms of Satoh distributions. One of the mass concentrations is identified as the optical nucleus (ON), another as the center of the bulge isophotes, similar to the CO kinematical center (KC), and the third as a condensation hidden at optical wavelengths (HN), coincident with the largest lobe in 10 micron emission. We run numerical simulations that take into account ON, KC and HN and four more clusters, representing the star forming arc at the SW of the optical nucleus. We show that ON, KC and HN suffer strong evaporation and merge in 10-50 Myr. The star-forming arc is scattered in less than one orbital period, also falling into the center. Simulations also show that tidal-striping boosts the external shell of the condensations to their escape velocity. This fact might lead to an overestimation of the mass of the condensations in kinematical observations with spatial resolution smaller than the condensations' apparent sizes. Additionally the existence of two ILR resonances embracing the chain of HII regions, claimed by different authors, might not exist due to the similarity of the masses of the different components and the fast dynamical evolution of M83 central 300 pc.
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