The Vega planetary system hosts the archetype of extrasolar Kuiper belts, and is rich in dust from the sub-au region out to 100's of au, suggesting intense dynamical activity. We present ALMA mm observations that detect and resolve the outer dust belt from the star for the first time. The interferometric visibilities show that the belt can be fit by a Gaussian model or by power-law models with a steep inner edge (at 60-80 au). The belt is very broad, extending out to at least 150-200 au. We strongly detect the star and set a stringent upper limit to warm dust emission previously detected in the infrared. We discuss three scenarios that could explain the architecture of Vega's planetary system, including the new {ALMA} constraints: no outer planets, a chain of low-mass planets, and a single giant planet. The planet-less scenario is only feasible if the outer belt was born with the observed sharp inner edge. If instead the inner edge is currently being truncated by a planet, then the planet must be $\gtrsim$6 M$_{\oplus}$ and at $\lesssim71$ au to have cleared its chaotic zone within the system age. In the planet chain scenario, outward planet migration and inward scattering of planetesimals could produce the hot and warm dust observed in the inner regions of the system. In the single giant planet scenario, an asteroid belt could be responsible for the warm dust, and mean motion resonances with the planet could put asteroids on star-grazing orbits, producing the hot dust.

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ALMA 解决了标志性织女星行星系统中的尘埃种群

织女星行星系统拥有太阳系外柯伊伯带的原型，并且富含从 sub-au 区域到 au 100's 的尘埃，表明强烈的动力活动。我们展示了 ALMA 毫米观测，首次探测并解析了来自恒星的外部尘埃带。干涉能见度表明该带可以通过高斯模型或具有陡峭内边缘（60-80 au）的幂律模型拟合。腰带很宽，延伸到至少 150-200 au。我们强烈地探测到这颗恒星，并为之前在红外线中探测到的暖尘排放设定了严格的上限。我们讨论了三种可以解释织女星行星系统架构的场景，包括新的 {ALMA} 约束：没有外行星、一系列低质量行星和一颗巨行星。只有当外带天生具有观察到的锐利内边缘时，无行星方案才可行。相反，如果内部边缘当前正被行星截断，则该行星必须是 $\gtrsim$6 M$_{\oplus}$ 和 $\lesssim71$ au 才能在系统时代清除其混乱区域。在行星链情景中，行星向外迁移和星子向内散射可能会产生在系统内部区域观察到的热尘埃。在单个巨行星的情况下，小行星带可能是造成温暖尘埃的原因，与行星的平均运动共振可能会使小行星进入掠星轨道，产生热尘埃。那么行星必须是 $\gtrsim$6 M$_{\oplus}$ 和 $\lesssim71$ au 才能在系统时代清除其混沌区域。在行星链情景中，行星向外迁移和星子向内散射可能会产生在系统内部区域观察到的热尘埃。在单个巨行星的情况下，小行星带可能是造成温暖尘埃的原因，与行星的平均运动共振可能会使小行星进入掠星轨道，产生热尘埃。那么行星必须是 $\gtrsim$6 M$_{\oplus}$ 和 $\lesssim71$ au 才能在系统时代清除其混沌区域。在行星链情景中，行星向外迁移和星子向内散射可能会产生在系统内部区域观察到的热尘埃。在单个巨行星的情况下，小行星带可能是造成温暖尘埃的原因，与行星的平均运动共振可能会使小行星进入掠星轨道，产生热尘埃。