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arXiv 0704.0203astro-ph
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斯皮策对IC 348星云的普查

A Spitzer census of the IC 348 nebula

August A. Muench, Charles J. Lada, K. L. Luhman, James Muzerolle, Erick Young

摘要:

我们提出了一个斯皮策为基础的普查IC 348星云和嵌入星团。我们的斯皮策普查补充地基光谱增加了42个II类T-Tauri源的集群成员和确定的~20 0/I类原恒星。IC 348的人口可能超过400个来源后,统计帐户的身份不明的无盘成员。我们的斯皮策普查IC 348揭示了人口的原恒星是反相关的空间与T-Tauri成员,其中包括中央凝聚的集群周围的B星。而原恒星大多数位于星团外围,距离B星约1 pc,并沿着一个边缘脊分布。我们发现,在这个原恒星脊的恒星形成率是一致的,建立暴露的集群,而存在的15个冷,无星,毫米的核心混合在这个原恒星人口表明,IC 348星云尚未完成形成恒星的速度。我们发现,IC 348集群是为了3-5交叉时代的老,并证明其平滑的径向轮廓和确认的质量偏析,可能是放松。虽然很明显,目前的集群配置是动态演化的结果,其原始结构已被删除,我们的研究结果支持嵌入式集群是从许多较小的子集群建立起来的模型。最后,我们的斯皮策普查结果表明,恒星形成必须在暗星云中快速进行的假设不应排除这些观测结果,这些观测结果表明它可以相对较长的寿命。

英文摘要:

We present a Spitzer based census of the IC 348 nebula and embedded star cluster. Our Spitzer census supplemented by ground based spectra has added 42 class II T-Tauri sources to the cluster membership and identified ~20 class 0/I protostars. The population of IC 348 likely exceeds 400 sources after accounting statistically for unidentified diskless members. Our Spitzer census of IC 348 reveals a population of protostars that is anti-correlated spatially with the T-Tauri members, which comprise the centrally condensed cluster around a B star. The protostars are instead found mostly at the cluster periphery about 1 pc from the B star and spread out along a filamentary ridge. We find that the star formation rate in this protostellar ridge is consistent with that rate which built the exposed cluster while the presence of fifteen cold, starless, millimeter cores intermingled with this protostellar population indicates that the IC 348 nebula has yet to finish forming stars. We show that the IC 348 cluster is of order 3-5 crossing times old, and, as evidenced by its smooth radial profile and confirmed mass segregation, is likely relaxed. While it seems apparent that the current cluster configuration is the result of dynamical evolution and its primordial structure has been erased, our findings support a model where embedded clusters are built up from numerous smaller sub-clusters. Finally, the results of our Spitzer census indicate that the supposition that star formation must progress rapidly in a dark cloud should not preclude these observations that show it can be relatively long lived.

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