Science nugget: Deformations in the velocity distribution functions of protons and alpha particles observed by Solar Orbiter in the inner heliosphere

18 January 2024 The solar wind is observed to be turbulent. Turbulence in plasmas involves a complex cross-scale coupling of fields, thus how the energy contained in the large-scale fluctuations of electromagnetic and velocity fields cascades all the way down to the kinetic scales, and how such turbulence interacts with particles, remain unsolved problems in... read more

Science nugget: Modelling Two Consecutive Energetic Storm Particle Events observed by Solar Orbiter

11 January 2024

Energetic Storm Particle (ESP) events are a type of solar energetic particle (SEP) events characterized by the rapid increase in the SEP intensity associated with a shock driven by a coronal mass ejection (CME). Two ESP events, both emanating from the same active region, were observed by the Solar Orbiter on August 31, 2022, and September 5,... read more

Science nugget: Understanding STIX hard X-ray source motions using field extrapolations

14 December 2023 We present key results of a case study of an M4-class flare on March 28, 2022, seen by STIX and EUI/FSI onboard Solar Orbiter, and SDO/AIA. An interesting aspect of this flare was the change in the non-thermal hard X-ray (HXR) source configuration during a late HXR peak, changing from the classical two footpoints at the ends of the flaring loops... read more

Science nugget: Multi-Spacecraft Observations of the 2022 March 25 CME and EUV Wave: An Analysis of their Propagation and Interrelation

7 December 2023 EUV waves are large-scale wave-like coronal disturbances visible in extreme ultraviolet (EUV) light. EUV waves arise from active regions (ARs) and are almost always associated with Coronal Mass Ejections (CMEs). The nature of EUV waves and their interrelation with CMEs is still debated. In the following, we investigate the nature of these... read more

Science nugget: EUI data reveal a "steady" mode of coronal heating

16 November 2023

In recent years, a consensus seems to have arisen that coronal heating is a dynamic process. For example, in De Moortel and Browning (2015) we read “coronal heating is intrinsically non-steady”. This point is not contested here, for it is well known that the energy input must be variable, being driven by granulation, emerging magnetic flux... read more

Science nugget: A new solution to the ambiguity problem

9 November 2023 Zeeman spectropolarimetry provides a method to infer the properties of the photospheric magnetic field, however, this is method is hampered by the 180°-ambiguity in the orientation of the transverse component: specifically two equally-intense, oppositely-directed transverse fields produce the very same spectro-polarimetric signal. The removal of... read more

Science nugget: Solar Orbiter and Parker Solar Probe jointly take a step forward in understanding coronal heating

2 November 2023 The photosphere exists at a temperature of around 6000 degrees. In the 1940s, following correct interpretation of solar spectra it was discovered that the temperature of the corona is instead about 150 times hotter, reaching one million degrees (coronal temperatures can even be an order of magnitude higher during high-energy events such as... read more

Science nugget: Observations of mini coronal dimmings caused by small-scale eruptions in the quiet Sun

25 October 2023 Solar eruptive activities, including flares, eruptive filaments, CMEs, and coronal jets, are widely distributed in energy scales. The observed solar eruptions span a range of at least a factor of 10⁸ in energy. Large, highly energetic “X-class” eruptions can release energy substantially exceeding ∼ 10³³ ergs. Coronal... read more

Science nugget: Fleeting small-scale surface magnetic fields build the quiet-Sun corona

18 October 2023 The solar corona is built by arch-like loop structures filled with million Kelvin hot plasma. The so-called active corona follows the 11-year solar activity cycle and is governed by strong magnetic concentrations in active regions including sunspots and plages. Powerful flares and coronal mass ejections are some of the transient signatures of... read more

Science nugget: Unusually long path length for a nearly scatter-free solar particle event observed by Solar Orbiter at 0.43 au

11 October 2023 On the 9th of April 2022 Solar Orbiter observed a virtually scatter-free solar particle event with an unusually long magnetic connection while immersed in a magnetic cloud. It was observed both in energetic electrons and ions while Solar Orbiter was at 0.43 au from the Sun. The length of the magnetic field line was inferred to be about three... read more