The solar corona is shaped and mysteriously heated to millions of degrees by the Sun’s magnetic field. It has long been hypothesized that the heating results from a myriad of tiny magnetic energy outbursts called nanoflares, driven by the fundamental process of magnetic reconnection. Misaligned magnetic field lines can break and reconnect, producing nanoflares in avalanche-like processes. However, no direct and unique observations of such nanoflares exist to date, and the lack of a smoking gun has cast doubt on the possibility of solving the coronal heating problem. From coordinated multi-band high-resolution observations, we report on the discovery of very fast and bursty nanojets, the telltale signature of reconnection-based nanoflares resulting in coronal heating. Using state-of-the-art numerical simulations, we demonstrate that the nanojet is a consequence of the slingshot effect from the magnetically tensed, curved magnetic field lines reconnecting at small angles. Nanojets are therefore the key signature of reconnection-based coronal heating in action.

太阳日冕的形状被太阳的磁场神秘地加热到数百万度。长期以来一直假设加热是由无数微小的磁能爆发引起的，这些爆发是在磁重连的基本过程的驱动下发生的，称为纳米光斑。错位的磁力线会断裂并重新连接，从而在类似雪崩的过程中产生纳米耀斑。然而，迄今为止，尚无关于这种纳米耀斑的直接和独特的观察结果，并且缺少吸烟枪已使人们对解决日冕加热问题的可能性产生怀疑。从协调的多波段高分辨率观测中，我们报告了非常快速且爆发性的纳米射流的发现，这是基于重新连接的纳米耀斑的明显特征，从而导致日冕加热。使用最新的数值模拟，我们证明了纳米喷射是弹弓效应的结果，该弹弓效应来自于以小角度重新连接的磁场张紧的弯曲磁场线。因此，纳米喷气机是基于重新连接的日冕加热的关键特征。