标题： 过渡盘SR 21毫米腔内的螺旋结构 显示英文标题

标题： Spirals inside the millimeter cavity of transition disk SR 21

摘要： 行星-盘相互作用的流体力学模拟表明，行星可能是散射光和尘埃热辐射中频繁观测到的许多子结构的成因。尽管这些特征普遍存在，但嵌入盘中的行星以及像行星间隙内的螺旋臂等特定相互作用特征的直接证据仍然很少见。在这项研究中，我们结合流体力学模拟讨论了最近的观测结果，以推断过渡盘空腔中假想嵌入行星的性质。我们使用SPHERE/IRDIS在H波段的散射光和ALMA 3毫米波段（波段3）在0.1角秒的空间分辨率下观测了过渡盘SR 21的热尘埃发射。我们将这些数据集与现有的波段9（430微米）和波段7（870微米）的ALMA连续谱数据相结合。波段3的连续谱数据显示出一个大的空腔和一个峰值位于53天文单位的明亮环，强烈暗示了尘埃捕获的存在。该环显示出显著的方位不对称性，在西北方向有一个明亮区域，我们认为这是尘埃密度过高的表现。在极化的散射光中同样揭示了在这个位置的另一个相似不对称的环，此外还有一组位于毫米空腔内部的明亮螺旋臂和一个较暗淡的螺旋桥连接外环。这些特征与先前多个行星-盘相互作用的流体力学模型一致，并暗示存在一颗约1木星质量、距离为44天文单位且位置角度（PA）为11{\deg }的行星。这使得SR21成为首个显示毫米空腔内螺旋臂的盘，也是可以精确推断假想行星位置的一个盘。由于观测已很好地约束了可能行星的位置，它是后续观测寻找仍嵌套于盘中的行星伴星的理想候选目标。 显示英文摘要

摘要： Hydrodynamical simulations of planet-disk interactions suggest that planets may be responsible for a number of the sub-structures frequently observed in disks in both scattered light and dust thermal emission. Despite the ubiquity of these features, direct evidence of planets embedded in disks and of the specific interaction features like spiral arms within planetary gaps still remain rare. In this study we discuss recent observational results in the context of hydrodynamical simulations in order to infer the properties of a putative embedded planet in the cavity of a transition disk. We imaged the transition disk SR 21 in H-band in scattered light with SPHERE/IRDIS and in thermal dust emission with ALMA band 3 (3mm) observations at a spatial resolution of 0.1". We combine these datasets with existing band 9 (430um) and band 7 (870um) ALMA continuum data. The Band 3 continuum data reveals a large cavity and a bright ring peaking at 53 au strongly suggestive of dust trapping.The ring shows a pronounced azimuthal asymmetry, with a bright region in the north-west that we interpret as a dust over-density. A similarly-asymmetric ring is revealed at the same location in polarized scattered light, in addition to a set of bright spirals inside the mm cavity and a fainter spiral bridging the gap to the outer ring. These features are consistent with a number of previous hydrodynamical models of planet-disk interactions, and suggest the presence of a ~1 MJup planet at 44 au and PA=11{\deg}. This makes SR21 the first disk showing spiral arms inside the mm cavity, as well as one for which the location of a putative planet can be precisely inferred. With the location of a possible planet being well-constrained by observations, it is an ideal candidate for follow-up observations to search for direct evidence of a planetary companion still embedded in its disk.