Local Stellar Kinematics from RAVE data—VII. Metallicity Gradients from Red Clump Stars
Local Stellar Kinematics from RAVE data—VII. Metallicity Gradients from Red Clump Stars
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DOI：
10.1017/pasa.2016.33
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发表时间：
2016-07
影响因子：
6.3
通讯作者：
O. O. Tas-O.;Selçuk Bilir;G. Seabroke;S. Karaali;Serap Ak;T. Ak;Z. F. Bostancı
中科院分区：
文献类型：
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作者：
O. O. Tas-O.;Selçuk Bilir;G. Seabroke;S. Karaali;Serap Ak;T. Ak;Z. F. Bostancı
摘要我们使用来自射电速度实验数据第4版的47406颗红团星的样本研究了银河系的径向和垂直金属丰度梯度。距离的计算方法是采用样本的Ks波段绝对星等为−1.54±0.04等。金属丰度梯度是用它们当前的轨道位置（R gc和Z）和它们的轨道性质（R m和z max）计算的：d[Fe/H]/dR gc = −0.047±0.003 dex kpc−1，|Z| ≤ 0.5 kpc且d[Fe/H]/dR m = −0.025±0.002 dex kpc−1（z max ≤ 0.5 kpc）。这再次证实了薄盘中的径向金属丰度梯度，但强调梯度对由R gc和R m之间的差异引起的选择效应敏感。径向梯度在距平面0.5-1 kpc的距离区间内是平坦的，然后在距平面大于1 kpc时变为正的。径向金属丰度梯度也与偏心率有关。我们发现，在距离间隔z max ≤ 0.5 kpc内，当e p ≤ 0.05、e p ≤ 0.07、e p ≤ 0.10和e p ≤ 0.20子样本时，d[Fe/H]/dR m = −0.089±0.010、−0.073±0.007、−0.053±0.004和−0.044±0.002 dex kpc−1。垂直金属丰度梯度也有类似的趋势。随着样品偏心率的增加，金属丰度的径向和垂直梯度都变浅。这些发现可以用来约束厚盘和薄盘的不同形成方案。
Abstract We investigate the Milky Way Galaxy’s radial and vertical metallicity gradients using a sample of 47 406 red clump stars from the RAdial Velocity Experiment Data Release 4. Distances are calculated by adopting Ks -band absolute magnitude as −1.54±0.04 mag for the sample. The metallicity gradients are calculated with their current orbital positions (R gc and Z) and with their orbital properties (R m and z max): d[Fe/H]/dR gc = −0.047±0.003 dex kpc−1 for |Z| ≤ 0.5 kpc and d[Fe/H]/dR m = −0.025±0.002 dex kpc−1 for z max ≤ 0.5 kpc. This reaffirms the radial metallicity gradient in the thin disc but highlights that gradients are sensitive to the selection effects caused by the difference between R gc and R m. The radial gradient is flat in the distance interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc from the plane. The radial metallicity gradients are also eccentricity dependent. We showed that d[Fe/H]/dR m = −0.089±0.010, −0.073±0.007, −0.053±0.004 and −0.044±0.002 dex kpc−1 for e p ≤ 0.05, e p ≤ 0.07, e p ≤ 0.10 and e p ≤ 0.20 sub-samples, respectively, in the distance interval z max ≤ 0.5 kpc. Similar trend is found for vertical metallicity gradients. Both the radial and vertical metallicity gradients are found to become shallower as the eccentricity of the sample increases. These findings can be used to constrain different formation scenarios of the thick and thin discs.