Volatile liquids (water, alcohol, etc.) poured on hot solids levitate above a layer of vapor. Unexpectedly, these so-called Leidenfrost drops often suddenly start to oscillate with star shapes, a phenomenon first reported about 140 y ago. Similar shapes are known to be triggered when a liquid is subjected to an external periodic forcing, but the unforced Leidenfrost case remains unsolved. We show that the levitating drops are excited by an intrinsic periodic forcing arising from a vibration of the vapor cushion. We discuss the frequency of the vibrations and how they can excite surface standing waves possibly amplified under geometric conditions of resonance—an ensemble of observations that provide a plausible scenario for the origin, mode selection, and sporadic nature of the Leidenfrost stars.

倾倒在热固体上的挥发性液体（水、酒精等）会悬浮在蒸汽层上方。出乎意料的是，这些所谓的莱顿弗罗斯特水滴经常突然开始以星形振荡，这种现象在大约 140 年前首次报道。已知当液体受到外部周期性强迫时会触发类似的形状，但非受迫莱顿弗罗斯特的情况仍未解决。我们表明悬浮液滴是由蒸汽垫振动引起的固有周期性强迫激发的。我们讨论了振动频率以及它们如何激发可能在共振几何条件下放大的表面驻波——一组观察结果为莱顿弗罗斯特星的起源、模式选择和零星性质提供了一个合理的场景。