Speaker
Description
Sunrise III/SCIP acquired a unique, high-precision spectropolarimetric dataset for a quiet Sun region near the disk center on 2024 July 11 with the full field of view of 58" x 58". With an integration time of 10 s per slit position, the scan was completed in 107 minutes without interruption, achieving a polarimetric precision of 0.03-0.04% (1$\sigma$). The multi-wavelength SCIP observations, covering both photospheric and chromospheric spectral lines in the 850 nm and 770 nm bands, reveal that the chromospheric line-of-sight magnetic field exhibits thread-like elongated structures over the internetwork regions of the quiet Sun. No clear photospheric counterpart is detected directly beneath these chromospheric thread-like structures. The threads are typically narrower than 1” and are embedded within the canopy fields extending from nearby network regions. Their line-of-sight field strengths derived from the weak-field approximation are typically 10-20 G weaker than the surrounding canopy fields. In particularly clear cases, the magnetic polarity of thread-like structures is opposite to that of the adjacent canopy field. These findings suggest that the canopy field is not a simple expanding structure originating from network regions but instead has a complex three-dimensional configuration containing numerous local dip structures. These observations provide new constraints on the three-dimensional magnetic topology of the photosphere and chromosphere in quiet-Sun regions.
In addition, we detect the blue and red excursions in the wing of the Ca II 854 nm line. These excursions sometimes coexist with the thread-like chromospheric magnetic field structures near network boundaries. We also discuss the relationship between the thread-like magnetic field structures and dynamics in the chromosphere.