Velocity Structure of Jets in Coronal Hole

TL;DR

This study uses Hinode's EIS data to analyze the velocity structures of coronal jets and bright points in a polar coronal hole, revealing upflows and magnetic reconnection signatures.

Contribution

First to derive velocity structures of coronal jets in a coronal hole using spectroscopic data from Hinode.

Findings

Jets are blue-shifted by up to 30 km/s indicating upflows.

Bright loop footpoints are red-shifted, suggesting downflows.

Magnetic reconnection is inferred as the jet driving mechanism.

Abstract

Velocity structures of jets in a coronal hole have been derived for the first time. Hinode observations revealed the existence of many bright points in coronal holes. They are loop-shaped and sometimes associated with coronal jets. Spectra obtained with the Extreme ultraviolet Imaging Spectrometer (EIS) on board Hinode are analyzed to infer Doppler velocity of bright loops and jets in a coronal hole of the north polar region. Elongated jets above bright loops are found to be blue-shifted by 30 km/s at maximum, while foot points of bright loops are red-shifted. Blue-shifts detected in coronal jets are interpreted as upflows produced by magnetic reconnection between emerging flux and the ambient field in the coronal hole.