Revision of Solar Spicule Classification

Zhang, Y. Z.; Shibata, Kazunari; Wang, J. X.; Mao, Xinjie; Matsumoto, Takuma; Liu, Yu; Su, Jiangtao

doi:10.1088/0004-637x/750/1/16

Cited by 67 publications

(54 citation statements)

References 49 publications

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“…They are now often called type II spicules, starting with De Pontieu et al (2007). Some objections regarding their significance were expressed (Zhang et al 2012;Klimchuk 2012); a more detailed and documented description was also given based on excellent ground-based SST spectroscopic observations and analysis (De Pontieu et al 2012) that we found agrees with much earlier results by Dara et al (1998). Indeed, type II spicules were also discussed in the framework of macro-spicules and even blow-out SXR coronal jets by Sterling et al (2010a,b), confirming that they are the components of a more significant event.…”

Section: Introductionsupporting

confidence: 90%

Alfvénic waves in polar spicules

Tavabi

Koutchmy

Ajabshirizadeh

et al. 2014

A&A

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Context. For investigating spicules from the photosphere to coronal heights, the new Hinode/SOT long series of high-resolution observations from space taken in CaII H line emission offers an improved way to look at their remarkable dynamical behavior using images free of seeing effects. They should be put in the context of the huge amount of already accumulated material from groundbased instruments, including high-resolution spectra of off-limb spicules. Aims. Both the origin of the phenomenon and the significance of dynamical spicules for the heating above the top of the photosphere and the fuelling of the chromospheric and the transition region need more investigation, including of the possible role of the associated magnetic waves for the corona higher up. Methods. We analyze in great detail the proper transverse motions of mature and tall polar region spicules for different heights, assuming that there might be Helical-Kink waves or Alfvénic waves propagating inside their multicomponent substructure, by interpreting the quasi-coherent behavior of all visible components presumably confined by a surrounding magnetic envelop. We concentrate the analysis on the taller CaII spicules more relevant for coronal heights and easier to measure. Two-dimensional velocity maps of proper motion were computed for the first time using a correlation tracking technique based on FFTs and cross-correlation function with a 2nd-order-accuracy Taylor expansion. Highly processed images with the popular mad-max algorithm were first prepared to perform this analysis. The locations of the peak of the cross-correlation function were obtained with subpixel accuracy. Results. The surge-like behavior of solar polar region spicules supports the untwisting multicomponent interpretation of spicules exhibiting helical dynamics. Several tall spicules are found with (i) upward and downward flows that are similar at lower and middle levels, the rate of upward motion being slightly higher at high levels; (ii) the left-and righthand velocities are also increasing with height; (iii) a large number of multicomponent spicules show shearing motion of both left-and righthanded senses occurring simultaneously, which might be understood as twisting (or untwisting) threads. The number of turns depends on the overall diameter of the structure made of components and changes from at least one turn for the smallest structure to at most two or three turns for surge-like broad structures. The curvature along the spicule corresponds to a low turn number similar to a transverse kink mode oscillation along the threads.

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Section: Introductionsupporting

confidence: 90%

Alfvénic waves in polar spicules

Tavabi

Koutchmy

Ajabshirizadeh

et al. 2014

A&A

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“…The proposal that spicules supply the corona with its mass is not new [ Athay and Holzer , 1982], but the idea was largely rejected because classical spicules are not observed to reach coronal temperatures. Although it is not universally accepted that type II spicules are different from classical spicules [ Zhang et al , 2012; Sterling et al , 2010], the new observations show that at least some hot material is transported to the corona during some ejections.…”

Section: Introductionmentioning

confidence: 97%

The role of type II spicules in the upper solar atmosphere

Klimchuk

2012

J. Geophys. Res.

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[1] We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions, <5% in the quiet Sun, and <8% in coronal holes). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T ≤ 0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so substantial coronal heating would be needed to maintain the high temperatures that are seen at all altitudes. We suggest that the corona contains a mixture of thin strands, some of which are populated by spicule injections, but most of which are not. A majority of the observed hot emission originates in non-spicule strands and is explained by traditional coronal heating models. However, since these models predict far too little emission from the LTR, most of this emission comes from the bulk of the spicule material that is only weakly heated and visible in He II (304 Å) as it falls back to the surface.

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“…Type I spicules have lifetimes between 3 and 7 min and exhibit up and downward motions with speeds of 20-50 km s −1 . De Pontieu et al (2007b) noted the existence of relatively faster (≈100 km s −1 ) and shorter lifetime (50 s) spicules, which they called Type-II spicules, however Zhang et al (2012) questioned whether spicules should be divided into two classes. A comprehensive study by Pereira et al (2012), using quiet Sun, coronal hole and active region datasets quantifies various properties of spicules which, reveal a bi-modal distribution of key properties which also suggests that there may indeed be two varieties of spicules.…”

Section: Introductionmentioning

confidence: 99%

High-cadence observations of spicular-type events on the Sun

Shetye

Doyle

Scullion

et al. 2016

A&A

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Context. Chromospheric observations taken at high-cadence and high-spatial resolution show a range of spicule-like features, including Type-I, Type-II (as well as rapid blue-shifted excursions (RBEs) and rapid red-shifted excursions (RREs) which are thought to be on-disk counterparts of Type-II spicules) and those which seem to appear within a few seconds, which if interpreted as flows would imply mass flow velocities in excess of 1000 km s −1 . Aims. This article seeks to quantify and study rapidly appearing spicular-type events. We also compare the multi-object multi-frame blind deconvolution (MOMFBD) and speckle reconstruction techniques to understand if these spicules are more favourably observed using a particular technique. Methods. We use spectral imaging observations taken with the CRisp Imaging SpectroPolarimeter (CRISP) on the Swedish 1-m Solar Telescope. Data was sampled at multiple positions within the Hα line profile for both an on-disk and limb location. Results. The data is host to numerous rapidly appearing features which are observed at different locations within the Hα line profile. The feature's durations vary between 10-20 s and lengths around 3500 km. Sometimes, a time delay in their appearance between the blue and red wings of 3-5 s is evident, whereas, sometimes they are near simultaneous. In some instances, features are observed to fade and then re-emerge at the same location several tens of seconds later. Conclusions. We provide the first statistical analysis of these spicules and suggest that these observations can be interpreted as the line-of-sight (LOS) movement of highly dynamic spicules moving in and out of the narrow 60 mÅ transmission filter that is used to observe in different parts of the Hα line profile. The LOS velocity component of the observed fast chromospheric features, manifested as Doppler shifts, are responsible for their appearance in the red and blue wings of Hα line. Additional work involving data at other wavelengths is required to investigate the nature of their possible wave-like activity.

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Revision of Solar Spicule Classification

Cited by 67 publications

References 49 publications

Alfvénic waves in polar spicules

Alfvénic waves in polar spicules

The role of type II spicules in the upper solar atmosphere

High-cadence observations of spicular-type events on the Sun

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