沃尔夫-拉叶星系中的大质量恒星形成：IV b。利用经验校准来计算氧气丰度
Massive star formation in Wolf-Rayet galaxies: IV b. Using empirical calibrations to compute the oxygen abundance
摘要：
我们已经进行了全面的多波长分析的样本20星暴星系，显示了大量的人口非常年轻的大质量恒星，其中大多数被归类为沃尔夫-拉叶（WR）星系。我们使用多波长数据分析了我们星系样本的光学/近红外颜色、电离气体的物理和化学性质、恒星、气体和尘埃含量、恒星形成率和相互作用程度（以及许多其他星系性质）。我们编制了41个独立的恒星形成区域-氧丰度在12+log（O/H）= 7.58和8.75之间-其中31个对电离气体的电子温度有直接的估计。本文仅提交给astro-ph，汇编了最常见的氧丰度经验校准，并将使用直接方法获得的这些星系中的化学丰度与通过经验校准获得的化学丰度进行了比较，正如Lopez-Sanchez & Esteban（2010 b）所发表的那样。我们发现（i）Pilyugin方法（Pilyugin，2001年a，b; Pilyugin & Thuan 2005），它考虑了R23和P参数，是最适合这些恒星形成星系的经验校准，（ii）Pettini和Pagel（2004年）提供的氧丰度与N2或O3 N2参数之间的关系，对于12+log（O/H）> 8.0，和（iii）的结果提供的经验校准的基础上光电离模型（McGaugh，1991年; Kewley & Dopita，2002年; Kobulnicky & Kewley，2004年）是系统的0.2 - 0.3倍高于直接方法得到的值。这些差异是相同的顺序，发现重组和碰撞激发线之间的丰度差异。这可能暗示了电离气体中存在温度波动，就像银河系和其他河外HII区域一样。
英文摘要：
We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show a substantial population of very young massive stars, most of them classified as Wolf-Rayet (WR) galaxies. We have analysed optical/NIR colours, physical and chemical properties of the ionized gas, stellar, gas and dust content, star-formation rate and interaction degree (among many other galaxy properties) of our galaxy sample using multi-wavelength data. We compile 41 independent star-forming regions --with oxygen abundances between 12+log(O/H) = 7.58 and 8.75--, of which 31 have a direct estimate of the electron temperature of the ionized gas. This paper, only submitted to astro-ph, compiles the most common empirical calibrations to the oxygen abundance, and presents the comparison between the chemical abundances derived in these galaxies using the direct method with those obtained through empirical calibrations, as it is published in Lopez-Sanchez & Esteban (2010b). We find that (i) the Pilyugin method (Pilyugin 2001a,b; Pilyugin & Thuan 2005) which considers the R23 and the P parameters, is the best suited empirical calibration for these star-forming galaxies, (ii) the relations between the oxygen abundance and the N2 or the O3N2 parameters provided by Pettini & Pagel (2004) give acceptable results for objects with 12+log(O/H)>8.0, and (iii) the results provided by empirical calibrations based on photoionization models (McGaugh, 1991; Kewley & Dopita, 2002; Kobulnicky & Kewley, 2004) are systematically 0.2 -- 0.3 dex higher than the values derived from the direct method. These differences are of the same order that the abundance discrepancy found between recombination and collisionally excited lines. This may suggest the existence of temperature fluctuations in the ionized gas, as exists in Galactic and other extragalactic HII regions.
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