论文标题

新发现的麦哲伦云星团的天体物理特性

Astrophysical properties of newly discovered Magellanic Cloud star clusters

论文作者

Piatti, Andrés E.

论文摘要

最近,从相对深的成像调查中发现了投影到大小麦芽云(L/SMC)的新明星群集候选者(L/SMC)。我们在这里使用麦哲伦恒星历史调查产生的PSF光度法对位于L/SMC外部区域的24个星团候选者进行了声音分析。除了一个例外,研究的对象是真正的恒星聚集体。一旦他们观察到的颜色数级图(CMD)在统计上被田间恒星的存在统计污染,并且与合成概率高于50 \%的恒星与合成CMDS相比,与成千上万的腐烂,距离,金属群体,星星质量和综合品的合成CMD相比,我们得出结论。从似然方法获得的最匹配的合成CMD的参数被用作星形群体物理特性。现在的恒星簇样品跨越了广泛的距离,从位于LMC前面的恒星簇到沿着麦哲伦桥的开始,再到SMC后面的群体。他们的年龄揭示了由于银河相互作用而沿银河形成的不同地层发作。根据它们的估计金属性和年龄,我们推测了在几乎最后一个Gyr(log(log /yr)$ \ $ 9.0 $ 9.0)中,这些星系之间存在相对金属缺陷的气体流,这使得在星系外围的年轻恒星簇形成。鄙视L/SMC的相互作用,研究的星形簇比以银河系的方式相似或更大,这表明潮汐效应在我们的银河系中相对重要。

New star cluster candidates projected toward the Large and Small Magellanic Clouds (L/SMC) have been recently discovered from relatively deep imaging surveys. We here conduct a sound analysis of 24 star cluster candidates located in the outer regions of the L/SMC using PSF photometry produced by the Survey of the Magellanic Stellar History. With only one exception, the studied objects resulted to be genuine stellar aggregates. We conclude on their physical reality once their observed color-magnitude diagrams (CMDs) were statistically decontaminated by the presence of field stars, and the resulting cleaned CMDs for stars with assigned membership probabilities higher than 50\% were compared with synthetic CMDs generated for thousand combinations of ages, distances, metallicities, star cluster mass and binary fractions. The parameter of the best-matched synthetic CMDs obtained from a likelihood approach were adopted as the star cluster astrophysical properties. The present star cluster sample spans a wide range of distances, from those star clusters located in front of the LMC, to those along the onset of the Magellanic Bridge, up to those behind the SMC. Their ages reveal different formation episodes that took place along the galaxy formation and others as a consequence of the galaxy interactions. From their estimated metallicities and ages, we speculate with the possibility that relatively metal-deficient gaseous flows have existed between these galaxies during nearly the last one Gyr (log(age /yr) $\approx$ 9.0), that made possible the formation of young star clusters in the galaxy peripheries. Despide the L/SMC interactions, the studied star clusters are similar or more massive than their counterparts in the Milky Way, which suggests that tidal effects are relatively more important in our Galaxy.

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