# The Sun and Space Weather
## 3 CME Source Regions, Flares, and Filaments  
The CME kinetic energy >10\({}^{33}\) erg has to be of magnetic origin [60]. Such huge amounts of energy can be stored and released in closed magnetic regions, such as sunspot regions. Closed magnetic fields also occur in non-spot regions called filament regions. Figure 5 shows examples of closed magnetic field regions at the three layers of the solar atmosphere: the photosphere, chromosphere, and corona. The compact magnetic regions are active regions (sunspot regions, but sometimes they can occur without a sunspot). One can identify five of them in Figure 5a, including the region marked A. Other regions are quiescent filament regions such as B, which also have enhanced but weaker magnetic fields than in active regions, and they are spatially more extended. Powerful CMEs can originate from both types of closed-field regions. Before eruption, bright loops can be found in the corona in both types of regions, although the active region loops are much brighter. At least some of these loops are incorporated into an erupting flux rope. Figure 6 shows an eruption from a weak field region (quiescent filament region). The region contains a horizontal filament, as imaged by the Nobeyama Radioheliograph (NoRH) at the heliographic location S54E46. In a subsequent image taken later in the day, the filament has disappeared. Such events are known as disappearing solar filament (DSF) events. In the corresponding EUV images, one can see similarities in the pre-eruption image, but after the filament disappears, there is diffuse brightening surrounding the original location of the filament. The diffuse brightening is the PEA. The erupted filament can be seen as the core of the associated CME, as shown in the 17:48 UT LASCO image. The  
Figure 5: A photospheric magnetogram from the Big Bear Solar Observatory (**a**), chromospheric (H-alpha) image from the Kanzelhohe Observatory (**b**), and a coronal (EUV) image from SOHO/EIT (**c**), all obtained on 13 May 2005. A large active region (A) and a filament region (B) are marked by arrows. In (**a**), black and white correspond to negative and positive magnetic polarity, respectively. In region A, the H-alpha image shows a sunspot, a reverse-S shaped dark filament, and bright plages, while in the region B the image shows just a dark filament. In the EUV images, active regions are bright compact features. Even the filament region shows surrounding faint loop arcade. The dark features in the EUV image are coronal holes. CME first appears in the LASCO FOV at 15:28 UT and has an average speed of 293 km/s. The CME accelerates throughout its passage of LASCO FOV, with an average acceleration of 15.9 m s\({}^{-2}\), attaining a speed of 524 km/s by the time it reaches \(\sim\)15 Rs. The PEA is so faint that it cannot be discerned in the GOES soft X-ray light curve, even though the background is very low (\(\sim\)A4.5). Figure 7 shows an active region eruption on 4 August 2011 imaged by the Nobeyama Radioheliograph and the Solar Dynamic Observatory's (SDO's) Atmospheric Imaging Assembly (AIA) at 193 A. The bright spot in the pre-eruption image at 03:20 UT is the sunspot in the active region emitting gyro-resonance emission. The active region contains a filament, which erupts. The image at 04:20 UT shows a large brightening, which is the PEA near the sunspot and the eruptive filament. This eruption results in a fast halo CME with an average speed of 1315 km/s and a large deceleration of \(-41.1\) km s\({}^{-2}\) in the LASCO FOV. To see the early morphology, we have shown the view from the inner STEREO coronagraph COR1, located west of the Sun-Earth line (W101). The CME can be seen above the northwest limb of the Sun with a small filament core. The GOES light curve shows a major flare with a peak X-ray intensity of M9.3. In comparing this eruption with the one on 6 October 1997 (Figure 6), we see similarities in various aspects, except for the higher magnitudes of various parameters in the active region eruption.