Dynamics of Sunspot Shock Waves in the Chromosphere and Transition Region
arXiv:2011.10192 · doi:10.3847/1538-4357/abcc6f
Abstract
We study the dynamics of shock waves observed in the umbra of a sunspot using the spectroscopic observations from the Interface Region Imaging Spectrometer (IRIS). The presence of the shock significantly deforms the shape of the spectral lines of Mg II , C II , and Si IV . We found that C II 1335.66 Å and Si IV 1393.75 Å show double-peaked profiles that change to a single peak later on. However, the Mg II h 2803.53 Å line first shows flat-top profiles that change into double-peaked followed by the single peak. To study the shock dynamics, we isolate the shock component from the spectra by fitting two Gaussians. We find that the lifetime of the shock is largest in Mg II h 2803.53 Å line. Moreover, the plasma motion shows both acceleration and deceleration phase of the shock. Yet, in C II 1335.66 Å and Si IV 1393.75 Å, only deceleration phase is observed. We observe a strong correlation between the largest blueshift of the shock and deceleration for all three spectral lines. We find a positive (negative) correlation between intensities contributed due to the shocks in Mg II and C II (Si IV ). This is suggestive that the shocks are first amplified in C II , followed by a decline in the height range corresponding to Si IV . These results may indicate the dissipation of shocks above the formation height of C II , and the shocks may have important roles in the dynamics of the upper chromosphere and transition region above sunspots.
arXiv comment20 Pages, 9 Figure, Accepted for Publication in ApJ
References in corpus (17)
- The Interface Region Imaging Spectrograph (IRIS)
- Observing the Roots of Solar Coronal Heating - in the Chromosphere
- The formation of IRIS diagnostics II. The formation of the Mg II h&k lines in the solar atmosphere
- Spectropolarimetric investigation of the propagation of magnetoacoustic waves and shock formation in sunspot atmospheres
- High-resolution Observations of the Shock Wave Behavior for Sunspot Oscillations with the Interface Region Imaging Spectrograph
- Alfvén Wave Dissipation in the Solar Chromosphere
- Velocity measurements for a solar active region fan loop from Hinode/EIS observations
- What do iris observations of Mg II k tell us about the solar plage chromosphere?
- The formation of IRIS diagnostics VI. The Diagnostic Potential of the C II Lines at 133.5 nm in the Solar Atmosphere
- Vertical Propagation of Acoustic Waves in the Solar Inter-Network as Observed by IRIS
- A closer look at a coronal loop rooted in a sunspot umbra
- Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
- Fan Loops Observed by IRIS, EIS and AIA
- Shock Heating Energy of Umbral Flashes Measured with Integral Field Unit Spectroscopy
- Propagation of Waves above a Plage as Observed by IRIS and SDO
- Wave amplitude modulation in fan loops as observed by AIA/SDO
- Direct observations of different sunspot waves influenced by umbral flashes