Monthly Archives: March 2018

93. Formation of Penumbra in A Sample of Active Regions Observed by the SDO Satellite

Contributed by Mariarita Murabito. Posted on March 29, 2018

Where does a sunspot’s penumbra start to form, on the same side or the opposite side of its opposite-polarity sunspot? When does Evershed flow start to appear, before or after the penumbral formation? These questions are answered through analyzing selected samples observed by the HMI.