Speaker: Juan Sebastián Castellanos-Durán (MPS, Germany) (Max Planck Institute for Solar System Research (MPS, Göttingen, Germany))

Title: On the extremes of solar spectropolarimetric data: Superstrong magnetic fields and extreme limb observations

Abstract: This talk focuses on the extremes of solar spectropolarimetric data and is divided into two parts that highlight recent observational advances.
The first part addresses superstrong magnetic fields in bipolar light bridges (BLBs). While previous observations noted rare cases of BLBs with extremely strong magnetic fields near 8.2 kG, it was unclear if this was the exception or the rule. By applying a state-of-the-art inversion technique to an extensive set of Hinode/SOT-SP data, we show that fields exceeding 4.0 kG, at the height of maximum magnetic sensitivity, with even higher field strengths in deeper layers. Our analysis shows that these superstrong fields are very common on the Sun and indicates that BLBs form a distinct physical population with a unique combination of continuum intensity and field strength, separate from standard umbrae and penumbrae.
In the second part, we move to the extreme solar limb to discuss low-straylight spectroscopy from the Sunrise III/SUSI stratospheric observatory. We analysed a scan reaching up to 6.5 Mm off-limb in the 407.6 to 410.25 nm wavelength range. We detected 174 spectral lines in emission, more than double what has been previously reported. Surprisingly, most of these lines begin showing emission while still on the disc, and a notable fraction come from rare-earth and heavy elements that normally show very weak absorption on-disc.

Note: Host: Meetu Verma

• Date:
  Sept. 3, 2026, 2:30 p.m. – 3:30 p.m.
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Julián Alvarado-Gómez
  julian.alvarado-gomez@aip.de