Spicules in IRIS Mg II Observations: Automated Identification

Abstract

We have developed an algorithm to identify solar spicules in the first ever systematic survey of on-disk spicules exclusively using Mg II spectral observations. Using this algorithm we identify 2021 events in three Interface Region Imaging Spectrograph (IRIS) data sets with unique solar feature targets spanning a total of 300 minutes: (1) active region, (2) decayed active region/active network, and (3) coronal hole. We present event statistics and relate occurrence rates to the underlying photospheric magnetic field strength. This method identifies spicule event densities and occurrence rates similar to previous studies performed using Hα and Ca II observations of active regions. Additionally, this study identifies spicule-like events at very low rates at magnetic field intensities below 20 G, and increasing significantly between 100 and 200 G in active regions and above 20 G in coronal holes, which can be used to inform future observation campaigns. This information can be be used to help characterize spicules over their full lifetimes, and compliments existing Hα spectral capabilities and upcoming Lyα spectral observations with the Solar eruptioN Integral Field Spectrograph (SNIFS) sounding rocket. In total, this study presents a method for detecting solar spicules exclusively using Mg II spectra, and provides statistics for spicule occurrences in the Mg II h line with respect to the magnetic field strength for the purpose of predicting spicule occurrences.

arXiv comment15 pages, 9 figures, presented at the AGU Fall 2022 conference, Submitted to APJ, published Apr 1 2023

References in corpus (30)

• The Interface Region Imaging Spectrograph (IRIS)
• The Solar Optical Telescope for the Hinode Mission: An Overview
• On Solving the Coronal Heating Problem
• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• A Tale Of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere
• Dynamic Fibrils are driven by Magnetoacoustic Shocks
• On the generation of solar spicules and Alfvénic waves
• On-disk counterparts of type II spicules in the Ca II 854.2 nm and Halpha lines
• Quantifying Spicules
• Solar fine-scale structures. I. Spicules and other small-scale, jet-like events at the chromospheric level: observations and physical parameters
• Generation of Solar Spicules and Subsequent Atmospheric Heating
• The formation of IRIS diagnostics I. A quintessential model atom of Mg II and general formation properties of the Mg II h&k lines
• An Interface Region Imaging Spectrograph first view on Solar Spicules
• Recent advances in coronal heating
• Nonlinear propagation of Alfven waves driven by observed photospheric motions: Application to the coronal heating and spicule formation
• Search for high velocities in the disk counterpart of type II spicules
• Magnetoacoustic shocks as driver of quiet Sun mottles
• Statistical properties of the Disk Counterparts of Type II Spicules from simultaneous observations of RBEs in Ca II 8542 and Hα
• Heating signatures in the disk counterparts of solar spicules in IRIS observations
• Kelvin-Helmholtz instability in solar chromospheric jets: theory and observation
• Quiet Sun Hα Transients and Corresponding Small-Scale Transition Region and Coronal Heating
• Spicules and downflows in the solar chromosphere
• Observed Variability of the Solar Mg II h Spectral Line
• On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS
• Magnetic Reconnection resulting from Flux Emergence: Implications for Jet Formation in the lower solar atmosphere?
• The Effects of Spatio-temporal Resolution on Deduced Spicule Properties
• Bridging the Gap: Capturing the Ly$\alpha$ Counterpart of a Type-II Spicule and its Heating Evolution with VAULT2.0 and IRIS Observations
• The chromosphere underneath a Coronal Bright Point
• Comparison of Solar Fine Structure Observed Simultaneously in Ly-α and Mg II h
• What Is the Source of Quiet Sun Transition Region Emission?