High-Resolution Observations and Modeling of Dynamic Fibrils

By Bart De Pontieu, V. Hansteen, L. R. V. Voort, M. Noort, M. C. L. M. S. Lab, P. Alto, Ca, USA., Institute for Theoretical Astrophysics, Oslo and 3 more. 2007

184 citations recorded by the source corpus.

We present unprecedented high-resolution Hα observations, obtained with the Swedish 1 m Solar Telescope, that, for the first time, spatially and temporally resolve dynamic fibrils in active regions on the Sun. These jetlike features are similar to mottles or spicules in quiet Sun. We find that most of these fibrils follow almost perfect parabolic paths in their ascent and descent. We measure the properties of the parabolic paths taken by 257 fibrils and present an overview of the deceleration, maximum velocity, maximum length, and duration, as well as their widths and the thickness of a bright ring that often occurs above dynamic fibrils. We find that the observed deceleration of the projected path is typically only a fraction of solar gravity and incompatible with a ballistic path at solar gravity. We report on significant differences of fibril properties between those occurring above a dense plage region and those above a less dense plage region where the magnetic field seems more inclined from the vertical. We compare these findings to advanced numerical two-dimensional radiative MHD simulations and find that fibrils are most likely formed by chromospheric shock waves that occur when convective flows and global oscillations leak into the chromosphere along the field lines of magnetic flux concentrations. Detailed comparison of observed and simulated fibril properties shows striking similarities of the values for deceleration, maximum velocity, maximum length, and duration. We compare our results with observations of mottles and find that a similar mechanism is most likely at work in the quiet Sun.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/62335ea170b219931bd761a1f63cafb5699ab41b

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Citations in the corpus

A Tale of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere (2007, methodology): “This linear correlation can be readily understood in terms of shock wave physics (De Pontieu et al., 2007b; Heggland, De Pontieu & Hansteen, 2007).”
The Interface Region Imaging Spectrograph (IRIS) (2012, background): “An instrument with these properties should be able to, e.g., quantify the properties of the waves that permeate this interface region (De Pontieu et al., 2007a; McIntosh et al., 2011; Okamoto and De Pontieu, 2011; De Pontieu et al., 2012; McIntosh and De Pontieu, 2012; Sekse et al., 2013) and…”
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).”
THE FORMATION OF THE Hα LINE IN THE SOLAR CHROMOSPHERE (2012, methodology): “…2007; Gudiksen et al. 2011) These models have been used to study various chromospheric phenomena, such as dynamic fibrils (Hansteen et al. 2006; De Pontieu et al. 2007a), the presence of Alfvénic waves (De Pontieu et al. 2007b), magnetic flux emergence (Mart́ınez-Sykora et al. 2008, 2009a) and…”
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.”
Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere (2007, methodology): “We have performed a two-dimensional simulation including non-equilibrium hydrogen ionization in a setup similar to the one used by Hansteen et al. (2006) and De Pontieu et al. (2007).”
UBIQUITOUS TORSIONAL MOTIONS IN TYPE II SPICULES (2012, methodology): “The cause of the heating and acceleration are unknown, but a magnetic process such as reconnection and/or flux emergence is most likely (De Pontieu et al. 2007b; Sterling et al. 2010; Mart́ınez-Sykora et al. 2011).”
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.”
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.”
HEATING OF THE SOLAR CHROMOSPHERE AND CORONA BY ALFVÉN WAVE TURBULENCE (2011, methodology): “The chromosphere is highly dynamic, and is filled with jet-like features such as mottles and dynamic fibrils on the solar disk (Rouppe van der Voort et al. 2007; De Pontieu et al. 2007a) and spicules at the limb (De Pontieu et al. 2007b).”