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arXiv 1003.0759astro-ph.GA
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行星状星云星族追踪的银河系结构和化学演化

The Galactic structure and chemical evolution traced by the population of planetary nebulae

L. Stanghellini, M. Haywood

摘要:

本文利用银河系行星状星云(PNe)的扩展数据集,研究了金属丰度梯度和银河系的结构与演化。最新的丰度,距离(麦哲伦云PNE校准)已被采用,连同一个新的同质形态分类,以表征不同的PN人口。我们确认,形态类有很强的相关性PN Peimbert的类型,也与他们的分布在银河景观。我们研究了银盘内α元素的分布,发现最佳选择的银盘总体,加上最可靠的PN距离标度,得到整个银盘样品的径向氧梯度为d[log(O/H)]/dR=-0.023 +-0.006dex/ kpc,d[log(O/H)]/dR= -0.035+-0.024,-0.023+-0.005,和-0.011+-0.013 dex/kpc。相同PN类型的霓虹灯梯度证实了这一趋势。精确的统计分析显示斜率的不确定性相当高,但也证实了PNE具有更大质量祖先的更陡梯度的趋势,表明银河系盘金属丰度梯度可能随着时间的推移而变陡。这里提出的PN金属丰度梯度与当地的金属丰度分布是一致的,此外,氧梯度与年轻和中间年龄PNe分别来自其他年轻(OB星,HII地区)和中间(疏散星团)银河系人口的氧梯度显示出良好的一致性。我们还扩展了银河系金属丰度梯度的比较,重新访问的疏散星团[Fe/H]的高分辨率光谱数据。分析表明,它们可能符合梯度随时间变陡的相同一般情况。

英文摘要:

We use an extended and homogeneous data set of Galactic planetary nebulae (PNe) to study the metallicity gradients and the Galactic structure and evolution. The most up-to-date abundances, distances (calibrated with Magellanic Cloud PNe) have been employed, together with a novel homogeneous morphological classification, to characterize the different PN populations. We confirm that morphological classes have a strong correlation with PN Peimbert's Type, and also with their distribution on the Galactic landscape. We studied the alpha-element distribution within the Galactic disk, and found that the best selected disk population, together with the most reliable PN distance scale yields to a radial oxygen gradient of d[log(O/H)]/dR=-0.023 +- 0.006 dex/ kpc for the whole disk sample, and of d[log(O/H)]/dR= -0.035+-0.024, -0.023+-0.005, and -0.011+-0.013 dex/kpc respectively for Type I, II, and III PNe. Neon gradients for the same PN types confirm the trend. Accurate statistical analysis show moderately high uncertainties in the slopes, but also confirm the trend of steeper gradient for PNe with more massive progenitors, indicating a possible steepening with time of the Galactic disk metallicity gradient. The PN metallicity gradients presented here are consistent with the local metallicity distribution; furthermore, oxygen gradients determined with young and intermediate age PNe show good consistency with oxygen gradients derived respectively from other young (OB stars, HII regions) and intermediate (open cluster) Galactic populations. We also extend the Galactic metallicity gradient comparison by revisiting the open cluster [Fe/H] data from high resolution spectroscopy. The analysis suggests that they could be compliant with the same general picture of a steepening of gradient with time.

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