64. Slow Appearance of Sunspots Challenges Theory
A comparison of the surface flow patterns in observation and numerical simulation suggests that the flux tube emerging speed has been overestimated in theories.
Category Archives: Magnetic Field
62. Tracing p-Mode Waves from the Photosphere to the Corona in Active Regions
Through analyzing a suite of space- and ground-based observations, the authors report that above sunspots, helioseismic waves of different frequencies are able to channel up through the chromosphere and transition region into corona. General pictures of how the waves make into corona are also shown.
59. The HMI Vector Magnetic Field Synoptic Charts
HMI now routinely produces vector magnetic field synoptic charts. This Nugget describes the data reduction procedures and the method chosen to resolve the 180-degree ambiguity in azimuth.
58. Signs of Cycle 25 Seen in the Surface Toroidal Field
Using a combination of the magnetograms, we find signs of the beginning of the 25th cycle from both HMI and WSO by calculating the inclination angles determined from the variation in line of sight field during a disk passage.
57. Formation of Large-Scale Inflows Into Active Regions
Large-scale inflows form around emerging solar active regions in the near-surface layer and alter the global meridional flow patterns.
56. A New Observing Scheme for HMI Vector Field Measurements: Mod-L
The HMI data-collection scheme was changed on 13 April 2016 to reduce noise in the vector magnetic field measurement. Starting at 19:24, the Stokes data series hmi.S_720s has been computed by combining filtergrams from both HMI cameras.
54. Data-Driven MHD Modeling of a Flux-Emerging Active Region Leading to Solar Eruption
A realistic MHD simulation driven directly by SDO/HMI vector magnetograms reproduced a solar eruption in a non-potential flux-emerging active region.
53. Observations of an X-shaped-ribbon Flare and Its Three-dimensional Magnetic Reconnection
An atypical X-shaped-ribbon flare provides evidence for 3D magnetic reconnection at a separator.
52. F10.7 Microwave Flux Matches the Total Disk Unsigned Magnetic Flux from MDI and HMI
The F10.7 microwave flux shows remarkabke agreement with the unsigned magnetic flux from MDI and HMI over the past 20 years, attesting to the accuracy and significance of both.
51. Magnetic Field Reconstruction Based on Sunspot Oscillations
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.