利用深空斯皮策成像追踪玫瑰星云中的恒星形成
Tracing star formation across the Rosette nebula using deep Spitzer imaging
- University of St Andrews（圣安德鲁斯大学）
- Universidade de Lisboa（里斯本大学）
- Univ. Bordeaux（波尔多大学）
- European Southern Observatory（欧洲南方天文台）
- Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Palermo（意大利国家天体物理研究所（INAF）- 巴勒莫天文台）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
基于深空斯皮策红外巡天数据，识别出1528个年轻恒星天体，分析其分布与Class I比例，揭示玫瑰星云中央恒星形成已停止，而外围环带正发生由膨胀HII区触发的恒星形成。
AI中文摘要：
我们展示了玫瑰星云中年轻恒星天体的大规模深空红外巡天结果。我们的分析基于堆叠的斯皮策/IRAC档案图像。这些图像已使用DeNeb软件处理以去除星云发射。我们的星表包含约20000个源，在3.6至8.0微米的所有4个IRAC波段均有测光数据，并辅以近红外和光学数据。从该数据库中，我们使用多滤光片颜色-颜色判据识别年轻恒星天体（YSOs）。我们选出1528个YSOs，其中1303个为Class II，225个为Class I。利用该样本，我们编制了玫瑰星云区域中YSO星团和群的列表，包括先前已知的，以及三个新识别的群。利用我们的YSO普查数据，结合文献，我们推导了星云中各星团的Class I比例和盘比例。中央空腔中的主要星团NGC 2244和NGC 2237几乎不含Class I源，表明该区域的恒星形成已停止。另一方面，在中心周围半径11-16秒差距的环带中，大致与膨胀的HII前沿重合，约30%的YSOs为Class I，这是正在进行的恒星形成的明显标志。云中更外围的其他群也表现出较高的Class I比例。盘比例中也观察到类似模式。我们的结果与膨胀的HII区域可能引发的恒星形成，以及电离前沿之外的恒星形成相一致。
英文摘要：
We present a deep large-scale infrared survey of young stellar objects in the Rosette Nebula. Our analysis is based on stacked archival Spitzer/IRAC images. The images have been treated with the software DeNeb to remove nebulous emission. Our catalogue contains ~20000 sources with photometry in all 4 IRAC bands from 3.6 to 8.0 microns, complemented with near-infrared and optical data. From this database, we identify YSOs using multi-filter colour-colour criteria. We select 1528 YSOs, from which 1303 are Class II and 225 are Class I. Using this sample, we compile a list of clusters and groups of YSOs in the Rosette region, including previously known ones, plus three newly identified groups. Using our census of YSOs, in combination with the literature, we derive the Class I ratios and disk fractions for clusters in the nebula. The main clusters in the central cavity, NGC 2244 and NGC 2237 are almost devoid of Class I sources, indicating that star formation has ceased in this area. On the other hand, in an annulus around the centre with radii of 11-16 pc, roughly coinciding with the expanding HII front, about 30% of the YSOs are Class I, a clear sign of ongoing star formation. Other groups further out in the cloud also exhibit a high Class I ratio. Similar patterns are seen in the disk fractions. Our results are consistent with possible triggering by the expanding HII region, combined with star formation beyond the ionisation front.
