郭守敬望远镜对Andromeda Galaxy的动力学和恒星星族性质的观测
Kinematics and Stellar Population Properties of the Andromeda Galaxy by the Spectroscopic Observations of the Guoshoujing Telescope
摘要：
在2009年的调试阶段，郭守敬望远镜（GSJT，前称大天区多目标光纤光谱望远镜- LAMOST）观测到了仙女座星系。由于缺乏标准星进行光通量定标，我们利用北京-亚利桑那-台北-康涅狄格巡天（BATC）的15个中间波段的光度数据进行光谱定标。在星系核球和盘中共获得59个光谱。用这些光谱导出了恒星含量的运动学和恒星星族性质。我们得到的全球速度场和计算相应的旋转速度外约7千秒差距沿主轴。这些旋转速度的测量补充了那些气体的内容，如H { \sc i}和CO。径向速度色散表明，在隆起的恒星更动态热和磁盘是更多的旋转支持。年龄分布表明，隆起形成于12 Gyr前，盘相对年轻，沿旋臂的某些区域的年龄可达1 Gyr左右。这些年轻的恒星星族具有相对丰富的丰度和较大的红化。银河系的总体平均金属丰度接近太阳金属丰度，丰度梯度很弱。变红的地图给出了一个无尘凸起和一个明显的尘埃环在磁盘中的图片。
英文摘要：
The Andromeda galaxy was observed by the Guoshoujing Telescope (GSJT, formly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope -- LAMOST) during the 2009 commissioning phase. Due to the absence of standard stars for flux calibration, we use the photometric data of 15 intermediate bands in the Beijing-Arizona-Taipei-Connecticut (BATC) survey to calibrate the spectra. Total 59 spectra located in the bulge and disk of the galaxy are obtained. Kinematic and stellar population properties of the stellar content are derived with these spectra. We obtain the global velocity field and calculate corresponding rotation velocities outer to about 7 kpc along the major axis. These rotation velocity measurements complement those of the gas content, such as the H {\sc i} and CO. The radial velocity dispersion presents that the stars in the bulge are more dynamically thermal and the disk is more rotation-supported. The age distribution shows that the bulge was formed about 12 Gyr ago, the disk is relatively younger, and the ages of some regions along the spiral arms can reach as young as about 1 Gyr. These young stellar populations have relatively richer abundance and larger reddening. The overall average metallicity of the galaxy approximates the solar metallicity and a very weak abundance gradient is gained. The reddening map gives a picture of a dust-free bulge and a distinct dusty ring in the disk.
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