标题： NGC 4038/4039中的恒星形成从宽波段和窄波段测光：星团破坏？ 显示英文标题

标题： Star-formation in NGC 4038/4039 from broad- and narrow band photometry: Cluster Destruction?

摘要： 准确确定星团合并中 NGC 4038/4039（“触须星系”）的恒星形成历史受到消光效应的阻碍。 因此，我们使用 ISAAC 在 VLT 和 SOFI 在 NTT 上获得的近红外图像来确定该合并中的近期恒星形成历史。 结合存档的哈勃太空望远镜 (HST) 数据，我们确定了单个星团的年龄、消光和其他参数，以及整个星团群体的属性。 大约 70% 的质量 ≥ 10^5 M_sun 且在 K_s 波段被探测到的星团年龄小于 10 百万年（大约是星团年龄的 e 折叠时间），我们认为这是快速溶解而非自由扩展的证据。 K 波段选择的星团总质量约为 5-10×10^8 M_sun，占总分子气体质量的 3-6%。 这仅考虑了被探测到的星团，并考虑到快速溶解效应，这意味着这只是爆发期间在星团中产生的恒星总质量的一个下限。 最近对其他星系中星团形成的研究所提出的短时间尺度星团溶解也表明，过去的恒星形成率可能被严重低估了。 消光效应变化强烈，在某些区域非常高，但平均约为 A_V=1.3 镑。 尽管大多数星团至少在 I 波段被探测到，但只有关于单个星团年龄和消光的信息才能避免从光学流量估算恒星形成率时出现数量级的不确定性。 根据个体星团消光与年龄分布的关系（对于低于 8-9 百万年的星团显著高于较老的星团），我们推断这是典型星团摆脱其原生尘埃茧的时间。 显示英文摘要

摘要： Accurately determining the star formation history in NGC 4038/4039 -- ``The Antennae'' is hampered by extinction. We therefore used near infrared images obtained with ISAAC at the VLT and with SOFI at the NTT to determine the recent star formation history in this merger. In combination with archival HST data, we determined ages, extinction and other parameters for single star clusters, and properties of the cluster population as a whole. About 70% of the K_s-band detected star clusters with masses >= 10^5 M_sun are younger than 10 Myrs (approximately an e-folding time for cluster ages), which we interpret as evidence for rapid dissolution but not free expansion. The total mass of K-band selected clusters is about 5-10x10^8 M_sun and represents about 3-6% of the total molecular gas. This takes into account only the detected clusters and in view of the rapid dissolution means that this is only a lower limit to the total mass of stars produced in clusters during the burst. Studies of cluster formation in other galaxies recently suggested short cluster dissolution timescales, too, which means that star formation rates may have been severely underestimated in the past. Extinction is strongly variable and very high in some regions, but around A_V=1.3 mag on average. Even though most clusters are detected at least in I-band, only the information about individual cluster ages and extinction allows to avoid uncertainties of orders of magnitude in star formation rate estimates determined from optical fluxes. From the distribution of individual cluster extinction vs. age, which is significantly higher for clusters below 8-9 Myr than for older clusters, we infer that this is the time by which a typical cluster blows free of its native dust cocoon.