Contribution to the modeling of solar spicules

Abstract

Solar limb and disc spicule quasi- periodic motions have been reported for a long time, strongly suggesting that they are oscillating. In order to clear up the origin and possibly explain some solar limb and disc spicule quasi-periodic recurrences produced by overlapping effects, we present a simulation model assuming quasi- random positions of spicules. We also allow a set number of spicules with different physical properties (such as: height, lifetime and tilt angle as shown by an individual spicule) occurring randomly. Results of simulations made with three different spatial resolutions of the corresponding frames and also for different number density of spicules, are analyzed. The wavelet time/frequency method is used to obtain the exact period of spicule visibility. Results are compared with observations of the chromosphere from i/ the Transition Region and Coronal Explorer (TRACE) filtergrams taken at 1600 angstrom, ii/ the Solar Optical Telescope (SOT) of Hinode taken in the Ca II H-line and iii/ the Sac-Peak Dunn's VTT taken in H{\alpha} line. Our results suggest the need to be cautious when interpreting apparent oscillations seen in spicule image sequences when overlapping is present, i.e.; when the spatial resolution is not enough to resolve individual components of spicules.Comment: 20 pages, 7 figures, 1 tabl

Revision of Solar Spicule Classification

“…The movements observed in filtergrams are thought to be related to the waves, such as kink waves and Alfvén waves (De Pontieu et al 2007b), and oscillations (Kulidzanishvili 1983). We notice that the space-time plot, which could reflect the dynamic information of spicule in a certain extent (Banerjee et al 2000;Christopoulou et al 2001;Tavabi et al 2011), was applied directly to measure the lifetime and height of a spicule in their study. For the real 3D motion of a spicule as mentioned above, especially the extensive lateral movement, a spicule could not always keep its motion in a fixed direction.…”

Alfvénic waves in polar spicules

“…If a magnetic field line reconnects with another field line, a magnetic tension force is generated in the reconnected field line as in a slingshot (described in e.g. Tavabi, Koutchmy & Ajabshirizadeh 2011c). Such a magnetic tension force accelerates plasmas in the reconnected field line up to the Alfvén speed outside the current sheet.…”

“…Therefore it is very likely that magnetic reconnection is a key to producing surges as also suggested for coronal polar jet (Patsourakos et al 2008). If a magnetic field line reconnects with another field line, a magnetic tension force is generated in the reconnected field line as in a slingshot (described in, e.g., Tavabi et al 2011c). Such a magnetic tension force accelerates plasmas in the reconnected field line up to the Alfvén speed outside the current sheet.…”

“…In these images a loop was seen at the feet of twisted spicules. Based on the conservation of rotational momentum (or helicities), we can expect that the expansion of chromospheric mini-loops finally leads to micro-eruptions similar to spicule eruption of the spine type (Tavabi et al 2011c). To go further with observations, some better S/N high-resolution frames are needed (Fig.…”

Hough Transform to Study the Magnetic Confinement of Solar Spicules

“…Of course, all these measurements suffered from overlapping effect of spicules seen along each line of sight, the effect of which will be more important when we look near the solar limb, see reference [17] for a model investtigation of this effect.…”