标题： ALMA对盘的成像：所有的间隙都是由行星雕刻的吗？ 显示英文标题

标题： ALMA images of discs: are all gaps carved by planets?

摘要： 原行星盘现在已经被常规观测到，而系外行星在众多间接发现之后，也开始被直接成像。 为了更好地理解行星形成过程，下一步是探测正在形成的行星，或者仍在其盘中的年轻行星的标志，例如间隙。 一个显著的例子是ALMA科学验证图像中HL Tau的显示，其盘中显示出许多间隙和环。 为了研究行星间隙的可观测性，我们运行了包含一个5个木星质量的开间隙行星的气体和尘埃盘的三维流体力学模拟，并表征了迁移、生长和碎裂尘粒的空间分布。 然后我们计算了相应的ALMA合成图像。 对于尘埃碰撞速度的碎裂阈值为15 m/s时，我们首次在考虑碎裂的模拟中识别出自引发的尘埃堆积。 这一特征，除了容易检测到的行星间隙外，还会导致第二个明显的间隙，可能会被误认为是第二个行星的信号。 因此，在解释间隙探测时必须谨慎。 显示英文摘要

摘要： Protoplanetary discs are now routinely observed and exoplanets, after the numerous indirect discoveries, are starting to be directly imaged. To better understand the planet formation process, the next step is the detection of forming planets or of signposts of young planets still in their disc, such as gaps. A spectacular example is the ALMA science verification image of HL Tau showing numerous gaps and rings in its disc. To study the observability of planet gaps, we ran 3D hydrodynamical simulations of a gas and dust disc containing a 5 M J gap-opening planet and characterised the spatial distribution of migrating, growing and fragmenting dust grains. We then computed the corresponding synthetic images for ALMA. For a value of the dust fragmentation threshold of 15 m s --1 for the collisional velocity, we identify for the first time a self-induced dust pile up in simulations taking fragmentation into account. This feature, in addition to the easily detected planet gap, causes a second apparent gap that could be mistaken for the signature of a second planet. It is therefore essential to be cautious in the interpretation of gap detections.