Bubbles, the semi-circular voids below quiescent prominences (filaments), have been extensively investigated in the past decade. However, to this point the magnetic nature of bubbles has been unverifiable due to the lack of on-disk photospheric magnetic field observations. Here for the first time, we find and investigate an on-disk prominence bubble around a filament barb on 2019 March 18 based on stereoscopic observations from the New Vacuum Solar Telescope (NVST), Solar Dynamics Observatory (SDO), and Spacecraft-A of the Solar TErrestrial RElations Observatory (STEREO-A). In high-resolution NVST Hα images, this bubble has a sharp arch-like boundary and a projected width of ∼26 Mm. Combining SDO and STEREO-A images, we further reconstruct 3D structure of the bubble boundary, whose maximum height is ∼15.6 Mm. The squashing factor Q map deduced from extrapolated 3D magnetic fields around the bubble depicts a distinct arch-shaped interface with a height of ∼11 Mm, which agrees well with the reconstructed 3D structure of the observed bubble boundary. Under the interface lies a set of magnetic loops, which is rooted on a surrounding photospheric magnetic patch. To be more persuasive, another on-disk bubble on 2019 June 10 is presented as a supplement. According to these results obtained from on-disk bubble observations, we suggest that the bubble boundary corresponds to the interface between the prominence dips (barb) and the underlying magnetic loops rooted nearby. Therefore, it is reasonable to speculate that the bubble can form around a filament barb below which there is a photospheric magnetic patch.

气泡，即静止突起（细丝）下方的半圆形空隙，在过去十年中得到了广泛的研究。然而，到目前为止，由于缺乏磁盘上光球磁场观测，气泡的磁性是无法验证的。根据新真空太阳望远镜 (NVST)、太阳动力学天文台 (SDO) 和航天器-A 的立体观测，我们首次在 2019 年 3 月 18 日发现并调查了围绕灯丝倒钩的磁盘上的日珥气泡。太阳地球关系天文台 (STEREO-A)。在高分辨率 NVST H α在图像中，这个气泡有一个尖锐的拱形边界和约 26 毫米的投影宽度。结合 SDO 和 STEREO-A 图像，我们进一步重建了气泡边界的 3D 结构，其最大高度为 15.6 毫米。压缩因子Q从气泡周围的外推 3D 磁场推导出的图描绘了一个独特的拱形界面，高度约为 11 毫米，这与观察到的气泡边界的重建 3D 结构非常吻合。在界面下方是一组磁环，它植根于周围的光球磁贴片上。为了更具说服力，2019 年 6 月 10 日的另一个磁盘泡沫作为补充提供。根据从磁盘气泡观察中获得的这些结果，我们建议气泡边界对应于日珥倾斜（倒钩）和在附近扎根的底层磁环之间的界面。因此，有理由推测气泡可以在灯丝倒钩周围形成，在灯丝倒钩下方有一个光球磁贴。