On Thermal-Pulse-Driven Plasma Flows in Coronal Funnels as Observed by Hinode/EUV Imaging Spectrometer (EIS)

TL;DR

This study combines high-resolution observations and numerical simulations to investigate plasma outflows in coronal funnels, suggesting magnetic reconnection-driven heating as a key mechanism for solar wind formation.

Contribution

It provides the first combined observational and simulation analysis of plasma flows in coronal funnels driven by thermal pulses, linking magnetic reconnection to solar wind initiation.

Findings

Open coronal funnels exhibit blue-shifted plasma flows of 10-15 km/s.

Numerical simulations show heating at funnel footpoints causes outward plasma perturbations.

Magnetic reconnection-induced heating likely triggers plasma outflows in coronal funnels.

Abstract

Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler velocity map of Fe XII 195.120 A shows that the diffuse close-loop system to be mostly red-shifted. The open arches (funnels) at the eastern boundary of AR exhibit blue-shifts with a maximum speed of about 10-15 km/s. This implies outflowing plasma through these magnetic structures. In support of these observations, we perform a 2D numerical simulation of the expanding coronal funnels by solving the set of ideal MHD equations in appropriate VAL-III C initial temperature conditions using the FLASH code. We implement a rarefied and hotter region at the footpoint of the model funnel, which results in the evolution of slow plasma perturbations propagating outward in the form of plasma flows. We conclude that the heating, which may result from magnetic reconnection, can trigger the observed plasma outflows in such coronal funnels. This can transport mass into the higher corona, giving rise to the formation of the nascent solar wind.