THE STRUCTURE AND METALLICITY GRADIENT IN THE EXTREME OUTER DISK OF NGC 7793
THE STRUCTURE AND METALLICITY GRADIENT IN THE EXTREME OUTER DISK OF NGC 7793
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DOI：
10.1088/0004-637x/732/1/7
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
M. Vlajić;J. Bland-Hawthorn;K. Freeman
中科院分区：
文献类型：
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作者：
M. Vlajić;J. Bland-Hawthorn;K. Freeman
对螺旋盘外部区域的研究对于我们理解星系的组装过程和随后星系的长期演化都是非常重要的。在之前的一系列文章中，我们探索了NGC300外盘的范围和丰度梯度，发现了一个扩展的纯指数盘，其金属丰度梯度在最外层区域变平。现在我们继续用另一个雕刻机群螺线NGC7793来研究纯圆盘螺线的外围。使用位于双子座南部的双子座多目标光谱仪相机，我们跟踪了NGC7793的圆盘，其恒星计数达到∼9标度长度，相当于11.5kpc，我们校准的距离为3.61±0.53mpc。NGC7793的外盘没有显示出其光轮廓断裂的证据，其有效表面亮度为∼30毫微弧秒−2(∼3毫微弧秒−2比表面光度法所获得的更深)，并且在我们的数据的径向范围内显示出非负的丰度梯度。
Studies of outer regions of spirals disks are fundamental to our understanding of both the process of galaxy assembly and the subsequent secular evolution of galaxies. In an earlier series of papers, we explored the extent and abundance gradient in the outer disk of NGC 300 and found an extended purely exponential disk with a metallicity gradient which flattens off in the outermost regions. We now continue the study of outskirts of pure disk spirals with another Sculptor Group spiral, NGC 7793. Using the Gemini Multi Object Spectrograph camera at Gemini South, we trace the disk of NGC 7793 with star counts out to ∼9 scale lengths, corresponding to 11.5 kpc at our calibrated distance of 3.61 ± 0.53 Mpc. The outer disk of NGC 7793 shows no evidence of a break in its light profile down to an effective surface brightness of ∼30 mag arcsec−2 (∼3 mag arcsec−2 deeper than what has been achieved with surface photometry) and exhibits a non-negative abundance gradient within the radial extent of our data.