Carbon and Oxygen Galactic Gradients: Observational Values from H II Region Recombination Lines
Carbon and Oxygen Galactic Gradients: Observational Values from H II Region Recombination Lines
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DOI：
10.1086/426889
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发表时间：
2004-08
期刊：
影响因子：
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通讯作者：
C. Esteban;J. García-Rojas;M. Peimbert;A. Peimbert;M. Ruiz;Mónica I. Rodríguez;L. Carigi
中科院分区：
文献类型：
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作者：
C. Esteban;J. García-Rojas;M. Peimbert;A. Peimbert;M. Ruiz;Mónica I. Rodríguez;L. Carigi
我们目前的结果，深阶梯分光光度法的8个银河系H II地区位于银河系的距离在6.3和10.4千秒差距。这些数据是用甚大望远镜紫外中阶梯摄谱仪在3100-10360 nm范围内拍摄的。我们已经从所有天体的复合线导出了C++和O++丰度，以及从三个星云的这种复合线导出了O+丰度。复合谱线的强度几乎与假设的电子温度以及星云内部可能存在的空间温度变化或波动无关。这些数据可以确定的气相C和O丰度梯度的银河系盘，化学演化模型的至关重要的。这是第一次从分布在如此广泛的银河系中心距离范围内的如此大量的H II区域中获得C梯度。吸收梯度的形式为Δ log（O/H）= -0.044 ± 0.010 dex kpc-1，Δ log（C/H）= -0.103 ± 0.018 dex kpc-1，Δ log（C/O）= -0.058 ± 0.018 dex kpc-1。
We present results of deep echelle spectrophotometry of eight Galactic H II regions located at Galactocentric distances between 6.3 and 10.4 kpc. The data have been taken with the Very Large Telescope Ultraviolet Echelle Spectrograph in the 3100-10360 Å range. We have derived C++ and O++ abundances from recombination lines for all the objects as well as O+ abundances from this kind of line for three of the nebulae. The intensity of recombination lines is almost independent of the assumed electron temperature as well as of the possible presence of spatial temperature variations or fluctuations inside the nebulae. These data allow the determination of the gas-phase C and O abundance gradients of the Galactic disk, of paramount importance for chemical evolution models. This is the first time the C gradient is derived from such a large number of H II regions distributed in such a wide range of Galactocentric distances. Abundance gradients are found of the form Δ log(O/H) = -0.044 ± 0.010 dex kpc-1, Δ log(C/H) = -0.103 ± 0.018 dex kpc-1, and Δ log(C/O) = -0.058 ± 0.018 dex kpc-1.