Energy and helicity injection in solar quiet regions

Abstract

Aims. We investigate the free magnetic energy and relative magnetic helicity injection in solar quiet regions. Methods. We use the DAVE4VM method to infer the photospheric velocity field and calculate the free magnetic energy and relative magnetic helicity injection rates in 16 quiet-Sun vector magnetograms sequences. Results. We find that there is no dominant sense of helicity injection in quiet-Sun regions, and that both helicity and energy injections are mostly due to surface shuffling motions that dominate the respective emergence by factors slightly larger than two. We, furthermore, estimate the helicity and energy rates per network unit area as well as the respective budgets over a complete solar cycle. Conclusions. Derived helicity and energy budgets over the entire solar cycle are similar to respective budgets derived in a recent work from the instantaneous helicity and free magnetic energy budgets and higher than previously reported values that relied on similar approaches to this analysis. Free-energy budgets, mostly generated like helicity at the network, are high enough to power the dynamics of fine-scale structures residing at the network, such as mottles and spicules, while corresponding estimates of helicity budgets are provided, pending future verification from high-resolution magneto-hydrodynamic simulations and/or observations.

The source and engine of coronal mass ejections

“…The plot of figure 7 implies a nearly monotonic dependence of free energy and relative helicity magnitude, with eruptive ARs statistically occupying its higher end-some exceptions are seen and discussed in [133]. The robustness of this diagram, even using quiet-Sun magnetograms and MHD simulations that did not rely on equations (3.14), (3.15), was demonstrated by Tziotziou and colleagues [37,134,135]. A case study of this was also the investigation of Patsourakos et al [136], where it was found that the exceptionally eruptive NOAA AR 11429 (figure 2) had equally exceptionally large values of free energy and relative helicity of a given (left-handed) sense.…”

Magnetic helicity and free magnetic energy as tools for probing eruptions in two differently evolving solar active regions

“…4.3 indicates that throughout the evolution of the ARs the prevelance of a particular helicity sign is far from overwhelming; in other words, the minority helicity sense (i.e., sign) has always a significant contribution to the net helicity budget. The helicity imbalance is similar to that of quiet Sun areas which are already known to show low degrees of imbalance (Tziotziou et al 2014(Tziotziou et al , 2015. In a separate study, it would be interesting to consider the degree of compliance of such spatially incoherent distributions of the signed components of helicity with the popular scenario that a deep-seated dynamo mechanism (e.g.…”

On the differences in the periodic behaviour of magnetic helicity flux in flaring active regions with and without X-class events

“…To test their conjecture, here, we have analyzed the EM, SH, and T magnetic helicity flux evolution of 14 flaring and 14 non-flaring ARs. Following the methodology of Korsós et al (2020), first we mitigated the artificial 12-and 24-hr periods of the SDO/HMI magnetogram measurements by set lower |±200| G and upper |±2000| G magnetic field boundaries for an AR, based on Smirnova et al (2013) and Tziotziou et al (2015). To further reduce the 12-and 24-hr SDO artifacts, we smoothed the time series of EM/SH/T with 24-hr smoothing window and subtracted the obtained averaging from the original data.…”

“…Additional constraints are applied to mitigate the artificial 12-and 24-hr periods of the SDO/HMI magnetogram measurements. Based on Smirnova et al (2013), the strength of the magnetic field is capped at a maximum of |±2000| G. We also impose a minimum threshold of |±200| G, which is commonly used in the literature (Tziotziou et al 2015).…”