Mannings V, Koerner D W, Sargent A I
Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena 91125, USA.
Nature. 1997 Aug 7;388(6642):555-7. doi: 10.1038/41505.
beta Pictoris is the best known example of a main-sequence star encircled by a tenuous disk. Optical and infrared images of beta Pic suggest that the disk is composed of dust grains which have been interpreted as the debris generated by the disruption of the asteroid-sized remnants of planet-formation processes. The star itself is relatively old, with an age in excess of 100 Myr. Here we present high-resolution millimetre-wave images of continuum and molecular-line emission from dust and gas surrounding a much younger star, MWC480: the stellar properties of MWC480 are similar to those of beta Pic, but its age is just 6Myr. The morphology of the circumstellar material and a comparison with the predictions of kinematic modelling indicate the presence of a rotating disk, gravitationally bound to the star. Moreover, the mass of the disk is greater than the minimum required to form a planetary system like our own. We therefore suggest that the disk around the young star MWC480 could be a progenitor of debris disks of the type associated with older stars such as beta Pic, and so holds much promise for the study of both the origin of debris disks and the early stages of the formation of planetary systems.
绘架座β星是一颗被稀薄圆盘环绕的主序星中最为人所知的例子。绘架座β星的光学和红外图像表明，该圆盘由尘埃颗粒组成，这些尘埃颗粒被解释为行星形成过程中与小行星大小的残骸解体产生的碎片。这颗恒星本身相对较老，年龄超过10亿年。在这里，我们展示了围绕一颗年轻得多的恒星MWC480的尘埃和气体的连续谱及分子线发射的高分辨率毫米波图像：MWC480的恒星属性与绘架座β星相似，但其年龄仅为600万年。恒星周围物质的形态以及与运动学模型预测结果的比较表明存在一个与恒星引力束缚的旋转圆盘。此外，该圆盘的质量大于形成像我们太阳系这样的行星系统所需的最小质量。因此，我们认为年轻恒星MWC480周围的圆盘可能是与绘架座β星等较老恒星相关的那种碎片盘的前身，所以对于研究碎片盘的起源和行星系统形成的早期阶段都很有前景。
