Transverse Oscillations in Chromospheric Mottles

Abstract

A number of recent investigations have revealed that transverse waves are ubiquitous in the solar chromosphere. The vast majority of these have been reported in limb spicules and active region fibrils. We investigate long-lived, quiet-Sun, on-disk features such as chromospheric mottles (jet-like features located at the boundaries of supergranular cells) and their transverse motions. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. The data set is comprised of simultaneous imaging in the Hα core, Ca ii K, and G band of an on-disk quiet-Sun region. Time-distance techniques are used to study the characteristics of the transverse oscillations. We detect over 40 transverse oscillations in both bright and dark mottles, with periods ranging from 70 to 280 s, with the most frequent occurrence at ∼165 s. The velocity amplitudes and transverse displacements exhibit characteristics similar to limb spicules. Neighboring mottles oscillating in-phase are also observed. The transverse oscillations of individual mottles are interpreted in terms of magnetohydrodynamic kink waves. Their estimated periods and damping times are consistent with phase mixing and resonant mode conversion.

Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions

“…In particular the periodic, transverse displacement of magnetic flux tubes in both the chromosphere (De Pontieu et al 2007; Kuridze et al 2012;Morton et al 2012) and in the corona (Tomczyk et al 2007;Erdélyi & Taroyan 2008). The chromospheric motions are somewhat better resolved as they are observed with high-resolution (<0.…”

MHD Wave Modes Resolved in Fine‐Scale Chromospheric Magnetic Structures

“…Prior to these modern high-resolution chromospheric observations, an abundance of MHD waves were expected to exist in the Sun's lower atmosphere since it is in essence an elastic/compressible medium permeated by strong magnetic fields that are constantly being stressed and perturbed by the magneto-convective motions generated below (see Chapter 25 for an overview of photospheric wave modes). In agreement with these predictions it has now been confirmed that there are indeed both Alfvénic and magneto-acoustic wave modes propagating along chromospheric waveguides at all times [e.g., De Pontieu et al, 2007;He et al, 2009a, b;Morton et al, 2012a;Kuridze et al, 2012Kuridze et al, , 2013, to name but a few].…”

“…They were identified in scientific literature as far back as the early 1970s [e.g., Alissandrakis & Macris, 1971;Sawyer, 1972]. ROSA investigations of kink waves in mottles by Kuridze et al [2012Kuridze et al [ , 2013 revealed transverse velocity amplitudes on the order of 8 − 11 km s −1 , which again are of the same order as found in spicules. The same is also true of kink waves detected in Rapid Blue-shifted Excursions in large scale statistical studies by Roupe van der Voort et al [2009] and Sekse et al [2012Sekse et al [ , 2013, where they found transverse velocity amplitudes in a similar range.…”

“…Now there is such an extensive data set for the damping rates of coronal kink waves, even more advanced statistical models are now being employed [e.g., Arregui et al, 2013;Verwichte et al, 2013;Arregui & Asensio Ramos, 2014]. In contrast, to date there have only been a few attempts at estimating the in situ damping rates of kink waves in the chromosphere [e.g., Kuridze et al, 2012;Morton, 2014]. The basis of support for the mechanism of resonant absorption to explain observed kink wave damping is mostly founded on two separate arguments.…”

On Modeling the Kelvin–Helmholtz Instability in Solar Atmosphere

“…This approach-exploring the conditions for emerging a KH instability of MHD high-modes in solar atmosphere eruptions-has to be applied to the recent observations of oscillations and waves in spicules and macro-spicules (e.g., Popescu et al 2007;Zaqarashvili 2011;Tavabi, Koutchmy, & Ajabshirizadeh 2011;Tsiropoula et al 2012;Pereira, De Pontieu & Carlsson 2013;Skogsrud, Rouppe van der Voort & De Pontieu 2014), mottles (Kuridze et al 2012(Kuridze et al , 2013, chromospheric evaporations and jets (Kuridze et al 2011;Doschek, Warren & Young 2013;Yurchyshyn et al 2014), surges (Liu 2008;Zheng et al 2013), and coronal X-ray jets (Chandrashekhar et al 2014a(Chandrashekhar et al , 2014b. No less challenging is the modeling of the KH instability in solar prominences with rotating motions (Su & van Ballegooijen 2013) and in solar tornado-like prominences (Panasenco, Martin & Velli 2014).…”