Evidence of multithermal nature of spicular downflows. Impact on solar atmospheric heating

Abstract

Spectroscopic observations of the emission lines formed in the solar transition region (TR) commonly show persistent downflows of the order of 10--15 km/s. The cause of such downflows, however, is still not fully clear and has remained a matter of debate. We aim to understand the cause of such downflows by studying the coronal and TR responses to the recently reported chromospheric downflowing rapid red shifted excursions (RREs), and their impact on heating the solar atmosphere. We have used two sets of coordinated data from SST, IRIS, and SDO for analyzing the response of the downflowing RREs in the TR and corona. To provide theoretical support, we use an already existing 2.5D MHD simulation of spicules performed with the Bifrost code. We find ample occurrences of downflowing RREs and show several examples of their spatio-temporal evolution, sampling multiple wavelength channels ranging from the cooler chromospheric to hotter coronal channels. These downflowing features are thought to be likely associated with the returning components of the previously heated spicular plasma. Furthermore, the TR Doppler shifts associated with them are close to the average red shifts observed in this region which further implies that these flows could (partly) be responsible for the persistent downflows observed in the TR. We also propose two mechanisms (a typical upflow followed by a downflow and downflows along a loop), from the perspective of numerical simulation, that could explain the ubiquitous occurrence of such downflows. A detailed comparison between the synthetic and observed spectral characteristics, reveals a distinctive match, and further suggests an impact on the heating of the solar atmosphere. We present evidence that suggests that at least some of the downflowing RREs are the chromospheric counterparts of the TR and lower coronal downflows.

arXiv comment20 pages, 10 figures, accepted for publication in Astronomy and Astrophysics. Abstract abridged due to arXiv requirements

References in corpus (58)

• The chemical composition of the Sun
• The Interface Region Imaging Spectrograph (IRIS)
• The stellar atmosphere simulation code Bifrost
• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• A Tale Of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere
• Prevalence of Small-scale Jets from the Networks of the Solar Transition Region and Chromosphere
• CMasher: Scientific colormaps for making accessible, informative and 'cmashing' plots
• 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
• Ubiquitous torsional motions in type II spicules
• Approximations for radiative cooling and heating in the solar chromosphere
• On-disk counterparts of type II spicules in the Ca II 854.2 nm and Halpha lines
• On the generation of solar spicules and Alfvénic waves
• Generation of Solar Spicules and Subsequent Atmospheric Heating
• An Interface Region Imaging Spectrograph first view on Solar Spicules
• Flocculent flows in the chromospheric canopy of a sunspot
• On red shifs in the transition region and corona
• RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
• Search for high velocities in the disk counterpart of type II spicules
• Interplay of three kinds of motion in the disk counterpart of type II spicules: up-flow, transversal and torsional motions
• Ubiquitous High Speed Transition Region and Coronal Upflows in the Quiet Sun
• 3D Temperature Mapping of Solar Photospheric Fine Structure Using Ca II H Filtergrams
• Statistical properties of the Disk Counterparts of Type II Spicules from simultaneous observations of RBEs in Ca II 8542 and Hα
• SSTRED: Data- and metadata-processing pipeline for CHROMIS and CRISP
• Heating signatures in the disk counterparts of solar spicules in IRIS observations
• Three-dimensional modeling of the Ca II H&K lines in the solar atmosphere
• Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
• The Dynamics of Rapid Redshifted and Blueshifted Excursions in the Solar Halpha line
• Fast approximation of angle-dependent partial redistribution in moving atmospheres
• Transverse Wave Induced Kelvin-Helmholtz Rolls in Spicules
• On The Doppler Velocity of Emission Line Profiles Formed in the "Coronal Contraflow" that is the Chromosphere-Corona Mass Cycle
• Partial redistribution in 3D non-LTE radiative transfer in solar atmosphere models
• Ion-neutral interactions and non-equilibrium ionization in the solar chromosphere
• Forward modeling of emission in SDO/AIA passbands from dynamic 3D simulations
• Observations and numerical models of solar coronal heating associated with spicules
• Emergence of granular-sized magnetic bubbles through the solar atmosphere. II. Non-LTE chromospheric diagnostics and inversions
• Observations Supporting the Role of Magnetoconvection in Energy Supply to the Quiescent Solar Atmosphere
• Impact of Type II Spicules in the Corona: Simulations and Synthetic Observables
• HST/STIS High Resolution Echelle Spectra of alpha Centauri A (G2 V)
• What causes the high apparent speeds in chromospheric and transition region spicules on the Sun?
• Quiet Sun Hα Transients and Corresponding Small-Scale Transition Region and Coronal Heating
• The quiet Sun average Doppler shift of coronal lines up to 2 MK
• The Appearance of Spicules in High Resolution Observations of Ca II H and H-alpha
• Is the sky the limit? Performance of the revamped Swedish 1-m Solar Telescope and its blue- and red-beam re-imaging systems
• Spicules and downflows in the solar chromosphere
• On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS
• Ambipolar diffusion in the Bifrost code
• On the multi-threaded nature of solar spicules
• Time Dependent Non-Equilibrium Ionization of Transition Region Lines Observed with IRIS
• Spectroscopic measurements of dynamic fibrils in the Ca {\small{II}} 8662 Å line
• Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes
• Resonant absorption in expanding coronal magnetic flux tubes with uniform density
• High-resolution observations of the solar photosphere, chromosphere and transition region. A database of coordinated IRIS and SST observations
• ALMA and IRIS Observations of the Solar Chromosphere I: an On-Disk Type II Spicule
• Disentangling flows in the solar transition region
• Chromospheric counterparts of solar transition region unresolved fine structure loops
• SolO campfires in SDO images
• Solar H-alpha features with hot onsets. IV. Network fibrils

Cited by in corpus (12)

• Numerical simulations and observations of Mg II in the solar chromosphere
• The chromosphere underneath a Coronal Bright Point
• On the formation of solar wind & switchbacks, and quiet Sun heating
• Solar surges related to UV bursts: Characterization through k-means, inversions and density diagnostics
• Properties of shock waves in the quiet Sun chromosphere
• Spectroscopic observation of a transition region network jet
• Evolution of dynamic fibrils from the cooler chromosphere to the hotter corona
• On the Response of the Transition Region and the Corona to Rapid Excursions in the Chromosphere
• Beyond small-scale transients: a closer look at the diffuse quiet solar corona
• Doppler shifts of spectral lines formed in the solar transition region and corona
• Dynamics of Explosive Events by Interface Region Imaging Spectrograph
• Quiet Sun Ellerman bombs as a possible proxy for reconnection-driven spicules