We observed magnetoacoustic waves propagating along the magnetic field lines of a sunspot. Based on the wave periods and atmospheric characteristics, we reconstructed the magnetic field topology of the sunspot.
The HMI team has developed several Python codes that can be used to conveniently analyze its many magnetic field data products. Check it out!
The magnetic twist of a flux rope is carefully calculated for an active region model. The flux rope is close to the threshold of helical kink instability and has powered a series of eruptions.
Tiny sunspots, or pores, might have escaped the observers during the Maunder minimum. However, they might have carried enough magnetic flux for the normal operation of a Babcock-Leighton-type dynamo.
Data-driven magnetofrictional model provides a more realistic description of the non-potential coronal magnetic field, but faces technical challenges that need to be addressed.
Omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision.
The effect of the spatial resolution of the boundary data on nonlinear force-free extrapolations is systematically explored for a solar case.
Multiple-wavelength high-resolution observations reveal running penumbral waves in the middle photosphere, with an apparent horizontal speed of up to 51 km/s.
A newly discovered, fast-moving wave propagates outward along sunspots’ radial direction and may provide new diagnostics of the sunspot subsurface structure.
A statistical study using HMI vector magnetograms predicts the fastest CME that an active region can produce based on its magnetic parameters.