A Tale of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere

By Bart De Pontieu, Scott W. McIntosh, V. Hansteen, M. Carlsson, C. Schrijver, T. Tarbell, A. Title, R. Shine, Y. Suematsu, S. Tsuneta and 4 more. 2007

345 citations recorded by the source corpus.

We use high-resolution observations of the Sun in Ca II H 3968 A from the Solar Optical Telescope on Hinode to show that there are at least two types of spicules that dominate the structure of the magnetic solar chromosphere. Both types are tied to the relentless magnetoconvective driving in the photosphere, but have very different dynamic properties. ``Type-I'' spicules are driven by shock waves that form when global oscillations and convective flows leak into the upper atmosphere along magnetic field lines on 3-7 minute timescales. ``Type-II'' spicules are much more dynamic: they form rapidly (in ~10s), are very thin (<200km wide), have lifetimes of 10-150s (at any one height) and seem to be rapidly heated to (at least) transition region temperatures, sending material through the chromosphere at speeds of order 50-150 km/s. The properties of Type II spicules suggest a formation process that is a consequence of magnetic reconnection, typically in the vicinity of magnetic flux concentrations in plage and network. Both types of spicules are observed to carry Alfven waves with significant amplitudes of order 20 km/s.

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/ed1016ee101a49d934d8d6e17afabea17828572c

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Citations in the corpus

An Observational Overview of Solar Flares (2011, methodology): “12 Type I and Type II as used here should not be confused with the met r-wave radio bursts (e.g., Wild et al. 1963), nor with the spicules (De Pontieu et al. 2007).”
Multiwavelength Studies of MHD Waves in the Solar Chromosphere (2015, background): “More recently, there has been the sub-classification of spicules into Type-I and Type-II varieties (De Pontieu et al. 2007b).”
Solar Fine-Scale Structures. I. Spicules and Other Small-Scale, Jet-Like Events at the Chromospheric Level: Observations and Physical Parameters (2012, methodology): “De Pontieu et al. (2007c) analyzed time series of Ca ii H images taken with a SOT broadband filter.”
THE FORMATION OF IRIS DIAGNOSTICS. II. THE FORMATION OF THE Mg ii h&k LINES IN THE SOLAR ATMOSPHERE (2013, result): “Our results are therefore not necessarily valid in circumstances where the thermodynamic state of the atmosphere changes over shorter timescales, such 13 as in flares (e.g., Hudson 2011) and type II spicules (e.g., De Pontieu et al. 2007; Pereira et al. 2012).”
Oscillations and Waves in Solar Spicules (2009, methodology): “Indeed, Hinode/SOT observations (De Pontieu et al. (2007a)) show some evidence of upward and downward propagating waves, with some partially standing waves being observed.”
PROPAGATING WAVES ALONG SPICULES (2011, methodology): “Because we require at least one full “wiggle” (i.e., a half period) during the spicule lifetime, we cannot measure the propagation or properties of the lower frequency waves (P > 100 s) that carry much more energy (De Pontieu et al. 2007a).”
ON-DISK COUNTERPARTS OF TYPE II SPICULES IN THE Ca ii 854.2 nm AND Hα LINES (2009, methodology): “This is similar to what De Pontieu et al. (2007c) observed in type II spicules.”
OBSERVING THE ROOTS OF SOLAR CORONAL HEATING—IN THE CHROMOSPHERE (2009, background): “The formation of these ubiquitous type II spicules has been attributed to magnetic reconnection (De Pontieu et al. 2007b; Langangen et al. 2008).”