Statistical properties of spicules in MURaM-ChE

TL;DR

This study compares the statistical properties of simulated spicules in the solar chromosphere with observations, demonstrating the self-consistent formation of both types in MURaM-ChE simulations without ambipolar diffusion.

Contribution

It provides the first detailed statistical comparison of type II spicules in 3D simulations with observations, confirming their realistic properties and formation mechanisms.

Findings

Simulated spicule properties broadly match observed data.

Both type I and II spicules form self-consistently in the simulation.

Spicules are formed without the need for ambipolar diffusion.

Abstract

Numerical simulations of the solar chromosphere have progressed towards reproducing spicules, which are transient features observed at the solar limb using spectral lines such as H$\alpha$, Ca II H&K, or Mg II h&k. Two types of spicules, referred to as types I and II, have been identified in observations and studied in previous numerical works. The statistics of type II spicules in 3D numerical simulations have not yet been studied. We aim to compare the statistics of properties such as lengths, lifetimes, widths, heights, inclinations, and maximum velocities of self-consistently formed spicules in a MURaM-ChE simulation with observations. We employ a H$\alpha$ proxy to identify fine-scale structures at the solar limb resembling spicules in a simulation of an enhanced network region. We track the evolution of 58 such features found in a 21-minute time sequence, and compare their dynamical and morphological properties with those derived from quiet-Sun observations using the Solar Optical Telescope (SOT) onboard the Hinode mission in the Ca II H spectral line. Previous studies have shown that spicules show very similar properties in Ca II H and H$\alpha$. The spicule-like structures found in the simulation have statistical properties which are broadly consistent with those observed with Hinode/SOT. In particular, we find evidence for the self-consistent formation of both type I and type II spicules within the simulation, even in the absence of ambipolar diffusion. We also investigate the properties of rapid blueshifted and redshifted excursions (RBEs and RREs) in the simulation in relation to the spicules.