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.
Highlights
The solar wind is the supersonic outflow of fully ionized gas from the solar corona streaming along the magnetic-field lines
We report the evidence of the outflowing magnetic arches acting as coronal funnels at the eastern boundary of an AR 10940 loop system observed on 5 February 2007
The scanning steps were without any offset in the region containing a coronal active region and its eastern boundary with open and expanding magnetic arches where we are interested in the present investigation
Summary
The solar wind is the supersonic outflow of fully ionized gas from the solar corona streaming along the magnetic-field lines. Schmidt and Ofman (2011) have found that the energy stored in the slow magnetoacoustic waves propagating toward the higher atmosphere within expanding loops This may be a potential candidate for the acceleration and formation of the slow solar wind. We report the evidence of the outflowing magnetic arches acting as coronal funnels at the eastern boundary of an AR 10940 loop system observed on 5 February 2007. These coronal funnels seem to open up in the higher atmosphere to transport the outflowing plasma. Their footpoints are rooted in the boundary of the active region.
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