Protostars, multiplicity, and disk evolution in the Corona Australis region: a Herschel Gould Belt Study
Protostars, multiplicity, and disk evolution in the Corona Australis region: a Herschel Gould Belt Study
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DOI：
10.1051/0004-6361/201220170
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发表时间：
2012-11
影响因子：
6.5
通讯作者：
A. Sicilia-Aguilar;T. Henning;H. Linz;P. Andre';A. Stutz;C. Eiroa;G. White
中科院分区：
文献类型：
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作者：
A. Sicilia-Aguilar;T. Henning;H. Linz;P. Andre';A. Stutz;C. Eiroa;G. White
上下文CrA区域和冕状星团形成了一个邻近的（138 pc），年轻的（1 - 2百万年）恒星形成区域，拥有中等数量的I，II和III类天体。我们研究了星团的结构和该地区的原恒星和原行星盘的性质。我们介绍了100和160 μm的Herschel PACS测光，作为Herschel Gould带巡天的一部分。Herschel图以高的灵敏度和高的动态范围揭示了星团内部的成员。许多星团成员被探测到，包括一些嵌入的，质量非常低的物体，几颗原恒星（其中一些是延伸的），以及来自周围分子云的大量发射。赫歇尔还揭示了一些引人注目的结构，例如IRS 5原恒星复合体周围的明亮细丝和与I类物体IRS 2相关的气泡状边缘。第二类天体周围的圆盘显示出与不同圆盘结构一致的广泛的中红外和远红外过度。我们已经模拟了磁盘的RADMC辐射传输代码，以量化其属性。其中一些是一致的耀斑，大规模的，相对原始的磁盘（S CrA，T CrA）。另一些则显示出由内而外进化的重要证据，与内部孔/间隙的存在相一致（G-85，G-87）。最后，我们发现磁盘与一个戏剧性的小灰尘耗尽（G-1，HBC 677），在某些情况下，可能与截断或存在的大差距，在一个喇叭形磁盘（CrA-159）。导出的低质量恒星周围的磁盘的质量被发现低于金牛座的典型值，与以前的斯皮策观测。结论.冕状星团是一个有趣的紧凑区域，包含年轻的原恒星和非常进化的圆盘。赫歇尔数据提供了足够的空间分辨率来探测小尺度的细节，例如与多颗星星形成有关的螺旋结构或螺旋臂。星系团成员周围的圆盘范围从大质量的，爆发的原始圆盘到具有大量小尘埃颗粒耗尽或具有由内而外进化证据的圆盘。这导致了年轻且可能是共演化形成的集群的有趣的物体混合物。鉴于在该区域的原恒星之间观察到的高度多样性和相互作用，盘的多样性可能是早期星星形成历史的结果，在研究类似的人口稀少的星团中的盘属性时也应考虑到这一点。
Context. The CrA region and the Coronet cluster form a nearby (138 pc), young (1−2 Myr) star-forming region that hosts a moderate population of Class I, II, and III objects.Aims. We study the structure of the cluster and the properties of the protostars and protoplanetary disks in the region.Methods. We present Herschel PACS photometry at 100 and 160 μm, obtained as part of the Herschel Gould Belt Survey. The Herschel maps reveal the cluster members within the cloud with high sensitivity and high dynamic range.Results. Many of the cluster members are detected, including some embedded, very low-mass objects, several protostars (some of them extended), and substantial emission from the surrounding molecular cloud. Herschel also reveals some striking structures, such as bright filaments around the IRS 5 protostar complex and a bubble-shaped rim associated with the Class I object IRS 2. The disks around the Class II objects display a wide range of mid- and far-IR excesses consistent with different disk structures. We have modeled the disks with the RADMC radiative transfer code to quantify their properties. Some of them are consistent with flared, massive, relatively primordial disks (S CrA, T CrA). Others display significant evidence for inside-out evolution, consistent with the presence of inner holes/gaps (G-85, G-87). Finally, we found disks with a dramatic small dust depletion (G-1, HBC 677) that, in some cases, could be related to truncation or to the presence of large gaps in a flared disk (CrA-159). The derived masses for the disks around the low-mass stars are found to be below the typical values in Taurus, in agreement with previous Spitzer observations. Conclusions. The Coronet cluster presents itself as an interesting compact region that contains both young protostars and very evolved disks. The Herschel data provide sufficient spatial resolution to detect small-scale details, such as filamentary structures or spiral arms associated with multiple star formation. The disks around the cluster members range from massive, flared primordial disks to disks with substantial small dust grain depletion or with evidence of inside-out evolution. This results in an interesting mixture of objects for a young and presumably coevally formed cluster. Given the high degree of multiplicity and interactions observed among the protostars in the region, the diversity of disks may be a consequence of the early star formation history, which should also be taken into account when studying the disk properties in similar sparsely populated clusters.