论文标题
混乱V：M101中的重组线碳丰度
CHAOS V: Recombination Line Carbon Abundances in M101
论文作者
论文摘要
混乱项目正在附近的螺旋星系中构建一个LBT H II区域光谱的大数据库，以使用直接丰度来更好地确定金属性的分散度，这是银河半径的函数。在这里，我们介绍了C II $λ$ 4267发射的混乱LBT观察结果，在M 101中的10 h II区域中检测到，并使用基于新光电离电模型的电离校正因子，我们将这些测量值转换为总碳含量。与文献中的M101 C II重组线观测值的比较显示出极好的一致性，并且我们测量了-0.37 +/- 0.06 dex/r_e的对数（C/H）的相对陡峭梯度。 C/N观测值与log（c/n）= 0.84的恒定值一致，仅分散0.09 dex，鉴于C和N的不同核合成来源，该dex的态度是挑战的。我们还注意到，当绘制N/O与O/H的绘制时，所有H II区域的检测为CII $λ$ 4267的检测，以o/h的n/o散射最小为n/o。如果将检测微弱的重组线所需的高表面亮度解释为H II地区青年的指标，那么这可能表明最年轻的H II区域缺乏氮污染。将来，我们预计混乱项目将显着增加CII $λ$ 4267 $ 4267的总数。
The CHAOS project is building a large database of LBT H II region spectra in nearby spiral galaxies to use direct abundances to better determine the dispersion in metallicity as a function of galactic radius. Here, we present CHAOS LBT observations of C II $λ$4267 emission detected in 10 H II regions in M 101, and, using a new photoionization model based ionization correction factor, we convert these measurements into total carbon abundances. A comparison with M101 C II recombination line observations from the literature shows excellent agreement, and we measure a relatively steep gradient in log(C/H) of -0.37 +/- 0.06 dex/R_e. The C/N observations are consistent with a constant value of log(C/N) = 0.84 with a dispersion of only 0.09 dex, which, given the different nucleosynthetic sources of C and N, is challenging to understand. We also note that when plotting N/O versus O/H, all of the H II regions with detections of CII $λ$4267 present N/O abundances at the minimum of the scatter in N/O at a given value of O/H. If the high surface brightness necessary for the detection of the faint recombination lines is interpreted as an indicator of H II region youth, then this may point to a lack of nitrogen pollution in the youngest H II regions. In the future, we anticipate that the CHAOS project will significantly increase the total number of C II $λ$4267 measurements in extragalactic H II regions.
