M83 延伸紫外盘内的年轻星团
Young star clusters in the extended UV disk of M83
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中文总结 AI 辅助
研究 M83 延伸紫外盘内 CO 团块的恒星形成，通过分析多波段图像识别团块内源并评估其与团块相关性，估计源质量，发现部分团块有恒星形成，且一个源与分子团块相互作用或引发更多恒星形成。
中文摘要 AI 辅助
低金属丰度环境中的恒星形成过程以及它是否与太阳附近的恒星形成不同是一个开放的课题。最近，在 M83 的延伸紫外线（XUV）盘中发现了 CO 团块，尽管其金属丰度低且距离星系中心较远，这使得可以在团块中寻找近期的恒星形成。我们旨在探究 XUV 盘中的 CO 团块内是否正在进行活跃的恒星形成，并评估其对这种环境中恒星形成的影响。我们分析了 Subaru Suprime - Cam 的深 Halpha 图像、Hyper Suprime - Cam 的 g、r 和 i 波段图像以及 Gemini/FLAMINGOS 2 的 J 和 Ks 波段图像，以寻找 ALMA 识别出的 CO 团块内恒星形成的证据。我们识别出 CO 团块轮廓内的源，并评估这些源与 CO 团块相关而非偶然对齐的概率。基于它们的星等并采用单年龄恒星群体模型，我们估计它们的质量。四个团块有相关的近红外对应体。基于它们的星等、颜色和场中的一般源密度，其中两个可能是偶然对齐。一个对应体与样本中最大质量的团块相关，而另一个是未解析的近红外星团源，估计年龄为 500 万年，质量为 2000 太阳质量。另一个扩展复合体与 600 万年的年龄和 700 太阳质量一致。近红外测光对质量低至几百太阳质量的年轻星团敏感，对于完全采样的初始质量函数。恒星形成正在一些 CO 团块中进行，尽管它们位于 M83 的外围，但至少在一些星团中仍存在有利于恒星形成的条件。其中一个检测到的源似乎正在与相邻的分子团块相互作用，这可能会引发进一步的恒星形成。
英文摘要
The process of star formation in a low-metallicity environment and whether it differs from star formation in the solar neighbourhood is an open topic. Recently, CO clumps were identified within the extended ultraviolet (XUV) disk of M83 despite the low metallicity and distance from the galaxy center which allows a search for any recent star formation in the clumps. We aim to probe whether active star formation is occurring within the CO clumps in the XUV disk, and to assess its implications for star formation in such environments. We analyse deep Subaru Suprime-Cam Halpha, Hyper Suprime-Cam g, r, & i, and Gemini/FLAMINGOS 2 J and Ks band imaging to search for evidence of star formation within the ALMA-identified CO clumps. We identify sources within the CO clump contours, and we evaluate the probability that these sources are associated with the CO clumps rather than being chance alignments. Based on their magnitudes and adopting single-age stellar population models, we estimate their masses. Four of the clumps have an associated near-infrared counterpart. Based on their magnitude, color, and the general source density in the field, two of these could be chance alignments. One counterpart is associated with the most massive clump in the sample, while another is an unresolved cluster near-infrared source with an estimated age of 5 Myr and a mass of 2000 Msun. The other, an extended complex, is consistent with an age of 6Myr and a mass of 700Msun. The near-infrared photometry is sensitive to young clusters with masses down to a few hundred of Msun for a fully sampled IMF. Star formation is ongoing in a few of the CO clumps, and despite their location on the outskirts of M83, favourable conditions for star formation persist in at least a few clusters. One of the detected sources appears to be interacting with an adjacent molecular clump, which could trigger further star formation.
