A Counterrotating Central Component in the Barred Galaxy NGC 5728
A Counterrotating Central Component in the Barred Galaxy NGC 5728
复制标题
棒星系 NGC 5728 中的反向旋转中心组件
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
C. Gutiérrez
中科院分区：
文献类型：
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作者：
F. Prada;C. Gutiérrez
利用I波段测光和近红外Ca II三重态长缝光谱观测，对棒星系NGC 5728的恒星运动学进行了详细的研究。对恒星视线速度分布（LOSVD）的分析表明，在棒的中心区域，存在一个冷的（v/σ~2.5）、反旋的、S形的速度分量，该分量在中心4kpc处与一个较暗和较热的（v/σ~0.5）反旋分量共存。在距核4kpc以外，LOSVD显示了恒星棒的运动学。速度分量的径向表面亮度轮廓与从I波段图像获得的比较表明，反向旋转的核心遵循r 1/4轮廓，而S形分量不遵循扁棒表面亮度轮廓。几种可能的方案占这样的运动学签名发现在中心的酒吧在NGC 5728进行了讨论。本文提供的数据首次表明，存在扩展的逆行运动在禁止系统，与以前的发现，似乎表明，恒星的反旋转是一种现象，目前所有沿着哈勃序列。
We present a detailed study of the stellar kinematics in the barred galaxy NGC 5728 based on I-band photometry and long-slit spectroscopic observations in the region of the near-IR Ca II triplet. The analysis of the stellar line-of-sight velocity distribution (LOSVD) has revealed, in the central regions of the bar, the presence of a cold (v/σ~2.5), prograde, S-shaped velocity component that coexists in the central 4 kpc, with a fainter and hotter (v/σ~0.5) counterrotating component. Beyond 4 kpc from the nucleus, the LOSVD shows the stellar bar kinematics. The comparison of the radial surface brightness profile of the velocity components with that obtained from an I-band image shows that the counterrotating core follows a r1/4 profile, while the S-shaped component does not follow the flat-bar surface brightness profile. Several possible scenarios accounting for such kinematic signatures found in the center of the bar in NGC 5728 are discussed. The data presented in this paper show for the first time the presence of extended retrograde motions in barred systems that, together with previous discoveries, seem to indicate that the stellar counterrotation is a phenomenon present all along the Hubble sequence.