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Emerging dimmings of active regions observed by SDO View all abstracts by submitter

Shuhong Yang   Submitted: 2012-10-18 21:50

With the observations from the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager aboard the emph{Solar Dynamics Observatory}, we statistically investigate the emerging dimmings (EDs) of 24 isolated active regions (IARs) from June 2010 to May 2011. All the IARs present EDs in lower temperature lines (e.g., 171 {AA}) at their early emerging stages, meanwhile in higher temperature lines (e.g., 211 {AA}), the ED regions brighten continuously. There are two type of EDs: fan-shaped and halo-shaped. There are 19 fan-shaped EDs and 5 halo-shaped ones. The EDs appear several to more than ten hours delay to the first emergence of the IARs. The shortest delay is 3.6 hr and the longest 19.0 hr. The EDs last from 3.3 hr to 14.2 hr, with a mean duration of 8.3 hr. Before the appearance of the EDs, the emergence rate of the magnetic flux of the IARs is from 1.2 imes 1019 Mx hr-1 to 1.4 imes 1020 Mx hr-1. The larger the emergence rate is, the shorter the delay time is. While the dimmings appear, the magnetic flux of the IARs ranges from 8.8 imes 1019 Mx to 1.3 imes 1021 Mx. These observations imply that the reconfiguration of the coronal magnetic fields due to reconnection between the newly-emerging flux and the surrounding existing fields results in a new thermal distribution which leads to a dimming for the cooler channel (171 {AA}) and brightnening in the warmer channels.

Authors: Jun Zhang, Shuhong Yang, Yang Liu, Xudong Sun
Projects: SDO-AIA,SDO-HMI

Publication Status: Accepted for publication in ApJL
Last Modified: 2012-10-19 09:56
Go to main E-Print page  Modeling Magnetic Field Structure of a Solar Active Region Corona using Nonlinear Force-Free Fields in Spherical Geometry  Magnetic Topology of Quiescent Prominence Bubbles  Edit Entry  Download Preprint  Delete Entry 

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