Transient microwave brightenings (TMBs) are small-scale energy releases from the periphery of sunspot umbrae, with a flux density two orders of magnitude smaller than that from a typical flare. Gopalswamy et al (1994) first reported the detection of the TMBs and it was pointed out that the radio emission implied a region of very high magnetic field so that the emission mechanism has to be gyror...

A number of methods of flare prediction rely on classification of physical characteristics of an active region, in particular optical classification of sunspots, and historical rates of flaring for a given classification. However, these methods largely ignore the number of flares the active region has already produced, in particular the number of small events. The past history of occurrence of ...

The relaxation dynamics of a magnetized plasma system is a subject of fundamental importance in magnetohydrodynamics—with applications ranging from laboratory plasma devices such as the toroidal-field pinch and spheromaks to astrophysical plasmas, stellar flaring activity, and coronal heating. Taylor in 1974 proposed that the magnetic field in a plasma, subject to certain constraints, relaxes t...

The Sun’s magnetic cycle manifests itself in an year periodic variation in the number of sunspots seen on the solar surface and a periodic reversal in the polarity of its large-scale magnetic fields. Exploring the origins of this magnetic cycle can unravel the physical mechanisms at work in the interior of magnetized stars like the Sun. Such studies are also important for understanding how the ...

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3 nm line taken with the CRisp Imaging Spectro-Polarimeter at the Swedish 1 m Solar Telescope. We compute Dopplergrams from the observed intensity profiles usi...

The relationship between bipolar magnetic regions (BMRs) and their sunspots is an important property of the solar field, but it not well constrained. One consequence that a challenge for surface flux transport models (SFTMs) based on sunspot observations to determine details BMR emergence, which they require as input, from such data. We aimed establish amount in newly emerged BMRs area enclosed...

Knowledge of solar variability and its effects on the Earth is essential since the Sun affects almost every aspect of our lives. Direct observations of the Sun, usually of sunspots, with some continuity, exist only since about 1700. Understanding of long-term solar variability must then depend on proxy data, such as visual auroral observations, measurements of magnetic activity, and the radioca...

Currently, astronomical data have increased in terms of volume and complexity. To bring out the information in order to analyze and predict, the artificial intelligence techniques are required. This paper aims to apply artificial intelligence techniques to predict M-class solar flare. Artificial neural network, support vector machine and naïve bayes techniques are compared to define the best pr...

We report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter on board the Hinode satellite. The downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly, and are associated with anomalous circular polarization profiles. An inversion of the observed Stokes spectra reveals veloci...

This paper shows that belief?driven economic fluctuations are a general feature of many determinate macroeconomic models. In environments with hidden state variables, forecast?model misspecification can break the link between indeterminacy and sunspots by establishing existence “statistical sunspots” in models have unique rational expectations equilibrium. To form expectations, agents regress o...