HIGH-RESOLUTION MID-INFRARED IMAGING OF THE CIRCUMSTELLAR DISKS OF HERBIG Ae/Be STARS
HIGH-RESOLUTION MID-INFRARED IMAGING OF THE CIRCUMSTELLAR DISKS OF HERBIG Ae/Be STARS
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HERBIG Ae/Be 星环星盘的高分辨率中红外成像
DOI：
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发表时间：
2011
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通讯作者：
C. Packham
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作者：
N. Marinas;C. Telesco;R. Fisher;C. Packham
我们已经用米歇尔在双子座北部和T-REC在双子座南部拍摄了17颗赫比格Ae/Be恒星在12和18μ米的环绕恒星环境。我们的样本包含8个I类源和9个II类源，前者具有较大的上升近红外(IR)通量，后者相对于其近IR通量具有较适中的中IR通量(在Meeus等人的分类中)。我们已经解决了我们目标清单中所有第一类污染源的延长排放问题。这些源中的大多数都有半径从10AU到数百AU的径向对称的中红外发射。在九个第二类污染源中，只有一个是在半高宽水平上分辨的，另外两个第二类污染源是在较暗的水平上分辨的。Dullemond等人的模型。解释使用自阴影冷盘观测到的第二类源的光谱能量分布。如果这是所有第二类来源的情况，我们预计不会在这项研究中探测到延长的发射，因为测量的红外发射应该来自只有几个AU大小的区域，这比我们的分辨率要小。我们确实解决了一些II类来源的问题，这意味着它们的盘并不是完全平坦的，可能代表了一个中间阶段。我们还发现，在我们的样本中，质量更大的(>；3 M☉)HerBig Ae/Be恒星都不属于第一类恒星，这可能表明恒星质量与恒星周围尘埃演化之间的关系。质量更大的恒星周围的圆盘可能演化得更快，因此当恒星变得可见时，它们被更进化的扁平圆盘所包围，或者它们可能遵循完全不同的进化路径。
We have imaged the circumstellar environments of 17 Herbig Ae/Be stars at 12 and 18 μm using MICHELLE on Gemini North and T-ReCS on Gemini South. Our sample contained eight Group I sources, those having large rising near- to far-infrared (IR) fluxes, and nine Group II sources, those having more modest mid-IR fluxes relative to their near-IR flux (in the classification of Meeus et al.). We have resolved extended emission from all Group I sources in our target list. The majority of these sources have radially symmetric mid-IR emission extending from a radius of 10 AU to hundreds of AU. Only one of the nine Group II sources is resolved at the FWHM level, with another two Group II sources resolved at fainter levels. Models by Dullemond et al. explain the observed spectral energy distribution of Group II sources using self-shadowed cold disks. If this is the case for all the Group II sources, we do not expect to detect extended emission with this study, since the IR emission measured should arise from a region only a few AU in size, which is smaller than our resolution. The fact that we do resolve some of the Group II sources implies that their disks are not completely flat, and might represent an intermediate stage. We also find that none of the more massive (>3 M☉) Herbig Ae/Be stars in our sample belongs to Group I, which may point to a relationship between stellar mass and circumstellar dust evolution. Disks around more massive stars might evolve faster so that stars are surrounded by a more evolved flat disk by the time they become optically visible, or they might follow a different evolutionary path altogether.