The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and...

An enormous solar tornado was observed by SDO/AIA on 25 September 2011. It was mainly associated with a quiescent prominence with an overlying coronal cavity. We investigate the triggering mechanism of the solar tornado by using the data from two instruments: SDO/AIA and STEREO-A/EUVI, covering the Sun from two directions. The tornado appeared near to the active region NOAA 11303 that produced ...

This paper deals with a feasibility study for a System-onChip (SoC) mm-wave radiometer devoted to space-based observation of solar flares and operating in the Ka-band. The radiometer has been designed in 250 nm SiGe BiCMOS process. The circuit integrates a three stages differential LNA with 37.2 dB gain and 4.8 dB noise figure at 36.8 GHz and a differential square-law detector based on HBTs, fe...

To address the role of energetic processes in the solar nebula, we provide a detailed characterization of magnetic flaring in stellar analogs of the pre-main sequence Sun based on two 0.5-day observations of analogs of the young Sun in the Orion Nebula Cluster obtained with the Chandra X-ray Observatory. The sample consists of 43 stars with masses 0.7-1.4 M⊙ and ages < 0.3 to ≃ 10 My. We find t...

We explore the spatio-temporal evolution of solar flares by fitting a radial expansion model r(t) that consists of an exponentially growing acceleration phase, followed by a deceleration phase that is parameterized by the generalized diffusion function r(t) ∝ κ(t − t1), which includes the logistic growth limit (β = 0), sub-diffusion (β = 0–1), classical diffusion (β = 1), super-diffusion (β = 1...

Of the many episodic variations associated with the active Sun, perhaps the solar flare is the most spectacular and enigmatic. Because flares emit photons that reach our atmosphere in about 8 minutes, with no intervening heliospheric or magneto spheric interactions, flare effects upon the geospace system have been a somewhat neglected component in Space Weather research. Once flare photons pass...

Because of instrumental sensitivity limits and stellar distances, the types of x-ray flares observable on stars have been intrinsically much more energetic than those on the sun. Such enormous events are a useful extrapolation of the solar phenomenon if the underlying assumption is correct that they form a continuous sequence involving similar physical processes as on the sun. The Advanced Sate...