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arXiv 2102.05244astro-ph.GA
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局域合并星系NGC 1487的物理和运动学条件

Physical and kinematic conditions of the local merging galaxy NGC 1487

M. L. Buzzo, B. Ziegler, P. Amram, M. Verdugo, C. E. Barbosa, B. Ciocan, P. Papaderos, S. Torres-Flores, C. Mendes de Oliveira

摘要:

本文给出了合并星系NGC 1487的光学VLT/MUSE积分场光谱数据。我们利用拟合技术研究了这次合并的电离气体发射及其主要的形态学和运动学性质。我们测量了组成NGC 1487的子系统中平坦的,有时是倒置的氧丰度梯度,这可以用合并星系中常见的金属混合过程来解释。我们还测量了广泛的恒星形成爆发,表明恒星的光电离是银河系的主要电离源。运动学图显示了该系统北尾气体的旋转模式,表明该星系可能正在重建一个圆盘。位于中心区域的气体具有较大的速度色散($σ\approx 50$ km s $^{-1}$)比其余地区,表明运动学加热,可能是由于正在进行的相互作用。然而,在恒星速度色散图中没有观察到类似的趋势,这表明星系尚未达到平衡,星云和恒星成分仍然在运动学上解耦。基于我们所有的测量和发现,特别是对系统的质量估计,金属丰度梯度和速度场,我们建议NGC 1487是一个正在进行的合并事件的结果,涉及一个集团内的小矮星系,在合并前阶段,导致一个遗迹的质量和物理参数类似于矮星系。因此,我们可能正在目睹一个矮星系的形成,它是由z=0的较小团块合并而成的。

英文摘要:

We present optical VLT/MUSE integral field spectroscopy data of the merging galaxy NGC 1487. We use fitting techniques to study the ionized gas emission of this merger and its main morphological and kinematical properties. We measured flat and sometimes inverted oxygen abundance gradients in the subsystems composing NGC 1487, explained by metal mixing processes common in merging galaxies. We also measured widespread star-forming bursts, indicating that photoionisation by stars is the primary ionization source of the galaxy. The kinematic map revealed a rotating pattern in the gas in the northern tail of the system, suggesting that the galaxy may be in the process of rebuilding a disc. The gas located in the central region has larger velocity dispersion ($σ\approx 50$ km s$^{-1}$) than the remaining regions, indicating kinematic heating, possibly owing to the ongoing interaction. Similar trends were, however, not observed in the stellar velocity-dispersion map, indicating that the galaxy has not yet achieved equilibrium, and the nebular and stellar components are still kinematically decoupled. Based on all our measurements and findings, and specially on the mass estimates, metallicity gradients and velocity fields of the system, we propose that NGC 1487 is the result of an ongoing merger event involving smallish dwarf galaxies within a group, in a pre-merger phase, resulting in a relic with mass and physical parameters similar to a dwarf galaxy. Thus, we may be witnessing the formation of a dwarf galaxy by merging of smaller clumps at z=0.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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