Dating the formation of the counter‐rotating stellar disc in the spiral galaxy NGC 5719 by disentangling its stellar populations★
Dating the formation of the counter‐rotating stellar disc in the spiral galaxy NGC 5719 by disentangling its stellar populations★
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DOI：
10.1111/j.1745-3933.2011.01016.x
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发表时间：
2011-01
影响因子：
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通讯作者：
L. Coccato;L. Morelli;E. Corsini;L. Buson;A. Pizzella;D. Vergani;F. E. S. Observatory;Garching;H Germany;D. Astronomia;U. Padova;Italy.;-INAF;O. Padova;Osservatorio Astronomico di Bologna
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文献类型：
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作者：
L. Coccato;L. Morelli;E. Corsini;L. Buson;A. Pizzella;D. Vergani;F. E. S. Observatory;Garching;H Germany;D. Astronomia;U. Padova;Italy.;-INAF;O. Padova;Osservatorio Astronomico di Bologna
我们展示了VLT/VIMOS对相互作用的螺旋星系NGC 5719内部28 × 28 arcsec 2 （3.1 × 3.1 kpc 2）的积分场光谱观测结果，该星系已知拥有两个共空间逆旋转恒星盘。在视场的每个位置，观测到的星系光谱被分解为两个恒星组分和一个电离气体组分光谱的贡献。我们测量了两颗恒星反向旋转分量的利克指数的运动学和线强度。我们用单个恒星人口模型来模拟每个恒星成分的数据，这些模型可以解释α/铁的过剩。我们还推导了电离气体盘的分布和运动学，它与较年轻、金属含量较低、α-增强较多和较不明亮的恒星成分有关。它们都相对于星系的主恒星体反向旋转。这些发现证明了这样一种假设，即NGC 5719首先通过与其伴星NGC 5713的相互作用，从邻近的大型储气库中吸积气体，并将其吸积到逆行轨道上，随后为反向旋转恒星盘的原位形成提供了燃料。
We present the results of the VLT/VIMOS integral-field spectroscopic observations of the inner 28 × 28 arcsec 2 (3.1 × 3.1 kpc 2 ) of the interacting spiral NGC 5719, which is known to host two cospatial counter-rotating stellar discs. At each position in the field of view, the observed galaxy spectrum is decomposed into the contributions of the spectra of two stellar and one ionized-gas components. We measure the kinematics and the line strengths of the Lick indices of the two stellar counter-rotating components. We model the data of each stellar component with single stellar population models that account for the α/Fe overabundance. We also derive the distribution and kinematics of the ionized-gas disc, that is associated with the younger, less rich in metals, more α-enhanced, and less luminous stellar component. They are both counter rotating with respect the main stellar body of the galaxy. These findings prove the scenario where gas was accreted first by NGC 5719 on to a retrograde orbit from the large reservoir available in its neighbourhoods as a result of the interaction with its companion NGC 5713, and subsequently fuelled the in situ formation of the counter-rotating stellar disc.