Morphological properties of slender Ca II H fibrils observed by SUNRISE II

TL;DR

This study uses high-resolution Ca II H data from SUNRISE to analyze the morphological properties of slender fibrils in the solar chromosphere, revealing their sizes, lifetimes, and curvature.

Contribution

It provides detailed measurements of slender Ca II H fibrils' properties using seeing-free high-resolution data, offering new insights into their morphology and dynamics.

Findings

Average width of 180 km for fibrils

Lifetimes up to 2000 seconds observed

Fibrils have an average curvature of 0.002 arcsec^-1

Abstract

We use seeing-free high spatial resolution Ca II H data obtained by the SUNRISE observatory to determine properties of slender fibrils in the lower solar chromosphere. In this work we use intensity images taken with the SUFI instrument in the Ca II H line during the second scientific flight of the SUNRISE observatory to identify and track elongated bright structures. After the identification, we analyze theses structures in order to extract their morphological properties. We identify 598 slender Ca II H fibrils (SCFs) with an average width of around 180 km, a length between 500 km and 4000 km, an average lifetime of ~400 s, and an average curvature of 0.002 arcsec^-1. The maximum lifetime of the SCFs within our time series of 57 minutes is ~2000 s. We discuss similarities and differences of the SCFs with other small-scale, chromospheric structures such as spicules of type I and II, or Ca II K fibrils.