Year: 2009
Type: article
Abstract: Using observations from the Solar and Heliospheric Observatory , the Solar Terrestrial Relations Observatory , and Hinode , we investigate magnetic field evolution in an equatorial coronal hole region. Two dipoles emerge one by one. The negative element of the first dipole disappears due to the interaction with the positive element of the second dipole. During this process, a jet and a plasma eruption are observed. The opposite polarities of the second dipole separate at first, and then cancel with each other, which is first reported in a coronal hole. With the reduction of unsigned magnetic flux of the second dipole from 9.8 × 10 20 Mx to 3.0 × 10 20 Mx in two days, 171 Å brightness decreases by 75% and coronal loops shrink obviously. At the cancellation sites, the transverse fields are strong and point directly from the positive elements to the negative ones, meanwhile Doppler redshifts with an average velocity of 0.9 km s −1 are observed, comparable to the horizontal velocity (1.0 km s −1 ) derived from the canceling island motion. Several days later, the northeastern part of the coronal hole, where the dipoles are located, appears as a quiet region. These observations support the idea that the interaction between the two dipoles is caused by flux reconnection, while the cancellation between the opposite polarities of the second dipole is due to the submergence of original loops. These results will help us to understand coronal hole evolution.
Source: The Astrophysical Journal
Authors: Shuhong Yang, Jun Zhang, Juan Manuel Borrero
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Aeronautics and Space Administration, National Science Council, Chinese Academy of Sciences, National Astronomical Observatory of Japan, Science and Technology Facilities Council, Japan Aerospace Exploration Agency, National Key Research and Development Program of China, National Astronomical Observatories, Chinese Academy of Sciences
Award: G1272654690
OpenAlex ID: W2111838426