Using Quadrature Observations from the STEREO and SOHO Satellites to Identify the Relationship Between Coronal Dimmings and CMEs

The goal of our project is to investigate the relationship between two solar phenomena: coronal dimmings and the associated coronal mass ejections (CMEs). Solar eruptions often lead to mass evacuation visible in EUV images (i.e. dimmings) as well as CMEs in off-disk images. Using images from the STEREO and SOHO satellites during their quadrature period in 2010, we achieved optimal observation of both phenomena, allowing for a more accurate computation of their properties. The SECCHI/EUVI instruments aboard STEREO A and B were used to observe dimmings in the 195 Angstrom wavelength, while the SOHO/LASCO instrument was used to create base-difference images to observe CMEs. Dimmings were processed using the Coronal Dimming Tracker (CoDiT, Krista & Reinard, 2017). This semi-automated tool tracks dimmings through their lifetime, allowing us to observe dimming evolution from its beginning to its end. The dimming observations were paired with the associated CME to identify a correlation between their observed properties and hence, better understand their relationship. In a study of Krista and Reinard (2017), poor correlation was found between dimming and CME properties. We hypothesize that the lack of correlation could have been due to errors in CME mass measurements. For this reason, we studied the above mentioned quadrature period where CMEs and dimmings were observed at right angles. Our study in this period allowed for a more accurate measurement of the CME masses. We found significant correlation between CME masses and certain dimming properties: dimming area (Pearson correlation = 0.7), mean EUV intensity (-0.7), and dimming lifetime (0.5).