The STARA catalog of sunspot properties from the SOHO/MDI and SDO/HMI data is presented and discussed. For STARA, an automated detection algorithm is employed to compile the first sunspot record from space-based instruments. This catalog is publicly available at http://www.nso.edu/staff/fwatson/STARA.
Flow system in an average supergranule is compared to the moat flow around axisymmetric sunspots. Both phenomena are very similar, only the outflow in the moat is distorted due to the proper motion of the sunspot with respect to the local frame of rest and moat is a purely downflow region.
Observed seismic upper bounds on large-scale lateral (horizontal) convective-velocity amplitudes in the solar interior at the depth r/R = 0.96 do not agree with modeling results derived at a similar depth from global convection simulations. The observations of low convective-velocity amplitudes throw into question our understanding of thermal and angular momentum transport in the Sun.
Multi-height Doppler velocity maps from two layers separated by 50 km are obtained from combinations of currently recorded HMI filtergrams. Using synthetic data of spectral line profiles produced in a convective environment, we test the ability to recover vertical velocity fields at different heights.
We attempt to forecast M- and X-class solar flares using a support vector machine algorithm and 4 years of HMI vector magnetic field data. With the true skill statistic as the preferred metric to estimate the algorithm performances, we obtain good predictive abilities. This may be partly due to fine-tuning the algorithm for this purpose, and to a choice of 13 SHARP parameters obtained from vector magnetograms.
Numerical simulations of solar rotation and dynamo have been performed over the last decades with the aim of understanding the physics of the solar interior. Here we briefly discuss two main approaches, namely, mean-field modeling and global simulations. We also present recent results of hydrodynamic global simulations which reveal interesting aspects of stellar rotation.
The magnetic field of active region NOAA 11092 shows a persistent counter-clockwise twist in the solar atmosphere from the photosphere to the corona. The subsurface flows associated with this region are twisted in the opposite direction.
New solar fluorine abundance was determined using improved molecular data. The new abundance is slightly lower than the old values previously determined in 1960s.
Combining the outstanding capability of HMI/SDO and NST/BBSO, we studied two rarely observed three-ribbon flares. The flaring site is characterized with an intriguing “fish-bone”-like morphology. These results are discussed in favor of reconnection along the coronal null-line.
Subsurface meridional flow speed shows an anti-correlation with the magnetic flux being transported poleward above the latitude of 35°. In the lower latitude, the residual meridional flow, after a long-time mean profile is subtracted, shows converging flow toward the activity belts.