Is there a metallicity gradient in the Large Magellanic Cloud
Is there a metallicity gradient in the Large Magellanic Cloud
复制标题
大麦哲伦云中是否存在金属丰度梯度
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
P. Whitelock
中科院分区：
文献类型：
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作者：
M. Feast;O. Abedigamba;P. Whitelock
根据 OGLE-III 调查数据，在大麦哲伦云 (LMC) RR Lyrae 变量的平均周期中建立了一个小但显着的径向梯度。这被解释为金属丰度梯度，但也讨论了其他可能性。 M-R 友情提供了 LMC 中光度选择的 C 型和 M 型渐近巨星分支 (AGB) 星的比例数据。 L. Cioni 进行了重新分析。消除偏见的影响会导致结论与原始结论截然不同。 LMC 内部的 C/M 比存在轻微的梯度，这可能是由于平均金属丰度梯度非常小。在 LMC 的外部，C/M 比率急剧下降。最可能的原因是外部区域老恒星的比例增加。根据 C/M 比估计的内部 AGB 星族的平均金属丰度低于中等年龄的 LMC 星团，表明该星族的平均年龄比星团更老，并且平均年龄落在 LMC 星团的年龄差距内。
A small but significant radial gradient in the mean periods of Large Magellanic Cloud (LMC) RR Lyrae variables is established from the OGLE-III survey data. This is interpreted as a metallicity gradient but other possibilities are also discussed. Data on the ratio of photometrically selected C- and M-type asymptotic giant branch (AGB) stars in the LMC, kindly provided by M-R. L. Cioni, are reanalysed. Removing the effects of bias leads to conclusions strikingly different to the original ones. There is a slight gradient of the C/M ratio in the inner part of the LMC, which might be due to a very small mean metallicity gradient. In the outer part of the LMC the C/M ratio drops dramatically. The most likely reason for this is that the proportion of older stars increases in the outer regions. The mean metallicity of the inner AGB star population estimated from the C/M ratio is lower than for intermediate age LMC clusters and suggest that this population is in the mean older than the clusters and has a mean age which falls in the LMC cluster age gap.