Probable identification of the on-disk counterpart of spicules in Hinode Ca II H observations

TL;DR

This study identifies the on-disk counterpart of spicules in Hinode Ca II H observations, linking network haze to type-II spicules through high-resolution imaging and spectral analysis.

Contribution

It provides the first probable identification of on-disk spicule counterparts, connecting observational features with simulated type-II spicules.

Findings

Network haze corresponds to spicules, likely type-II.

Strongest network haze occurs where type-II spicule simulations produce features.

Ca II H and Fe I line core intensities are highly correlated.

Abstract

I present a study of high-resolution time series of Ca II H images and Fe I 630.15 nm spectra taken with the Solar Optical Telescope on the Hinode spacecraft. There is excellent correspondence between the Ca II H and Fe I line core intensity, except tenuous emission around the network field concentrations in the former that is absent in the latter. Analysis of on-disk observations and a comparison with limb observations suggests that this "network haze" corresponds to spicules, and likely to type-II spicules in particular. They are known to appear in emission in on-disk broadband Ca II H diagnostics and the network haze is strongest in those areas where features similar to type-II spicules are produced in simulations.