The Effects of Transients on Photospheric and Chromospheric Power Distributions

Abstract

We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, Hα line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as "magnetic shadows." These also show enhanced power close to the photosphere, traditionally referred to as "power halos." The interaction between acoustic waves and inclined magnetic fields is generally believed to be responsible for these two effects. In this study we explore whether small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs), and Rapid Redshifted Excursions (RREs), can strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.

Accurately constraining velocity information from spectral imaging observations using machine learning techniques

“…using a double Voigt model), then the resulting Doppler velocities inferred from the emission Voigt fit are shown in the right panel of figure 7. In particular, it can be seen in the right panel of figure 7 that many of the derived Doppler velocities associated with dynamic phenomena appear to rapidly change between neighbouring pixels, an effect that has been documented in previous velocity studies of the solar chromosphere [58][59][60]. These rapid velocity excursions appear to be closely linked to instances when the Ca II 8542 Å line goes into emission.…”

An overall view of temperature oscillations in the solar chromosphere with ALMA

“…The pronounced 3-min fluctuations have often been observed in the line-of-sight velocity and/or intensity signals, in both quiet and active regions, through chromospheric spectral lines such as Ca II H & K [27][28][29][30], Ca II infrared triplet [30][31][32][33], Hα [34], He I 1083 nm [28,35,36] and Mg II h & k [37]. In the quiet Sun, while the 3-min oscillations have been shown in many observations of the low-to-mid chromosphere (or using relatively broad-band filters), a lack of such fluctuations in intensity image sequences of Hα line-core observations have also been reported [38]. Samanta et al [38] showed, however, that the dominating 3-min oscillations could be detected in the line-of-sight velocities of their Hα observations (i.e.…”

“…In the quiet Sun, while the 3-min oscillations have been shown in many observations of the low-to-mid chromosphere (or using relatively broad-band filters), a lack of such fluctuations in intensity image sequences of H α line-core observations have also been reported [38]. Samanta et al [38] showed, however, that the dominating 3-min oscillations could be detected in the line-of-sight velocities of their H α observations (i.e. also at the same spectral line position; the H α line-core), but not in the intensity.…”

An overall view of temperature oscillations in the solar chromosphere with ALMA

“…In the quiet Sun, while the 3-min oscillations have been shown in many observations of the low-to-mid chromosphere (or using relatively broad-band filters), a lack of such fluctuations in intensity image sequences of Hα line-core observations have also been reported [38]. Samanta et al [38] showed, however, that the dominating 3-min oscillations could be detected in the line-of-sight velocities of their Hα observations (i.e., also at the same spectral line position; the Hα line-core), but not in the intensity. In the latter, they found the dominant periods (in the entire field-of-view) to be longer than five minutes.…”

“…The pronounced 3-min fluctuations have often been observed in the line-of-sight velocity and/or intensity signals, in both quiet and active regions, through chromospheric spectral lines such as Ca II H & K [27][28][29][30], Ca II infrared triplet [30][31][32][33], Hα [34], He I 1083 nm [28,35,36], and Mg II h & k [37]. In the quiet Sun, while the 3-min oscillations have been shown in many observations of the low-to-mid chromosphere (or using relatively broad-band filters), a lack of such fluctuations in intensity image sequences of Hα line-core observations have also been reported [38]. Samanta et al [38] showed, however, that the dominating 3-min oscillations could be detected in the line-of-sight velocities of their Hα observations (i.e., also at the same spectral line position; the Hα line-core), but not in the intensity.…”