Is the Standard Flare Model Still Adequate? -- A Review of Recent RHESSI X-Ray Observations

The standard flare model was developed several decades ago. Many observations support this model. However, some aspects of the model are either contradicted by observations or lack observational support. It is these "imperfect matches" that offer a chance to refine the existing model and push it to higher levels of sophistication. The Ramaty High Energy Solar Spectroscopic Imager (RHESSI), with its unprecedented imaging capability, broad energy coverage and high energy resolution in X-rays, has provided us with many new observations of solar flares. This talk will focus on some of these results, from RHESSI alone and from RHESSI combined with other components of the Sun-Solar System Connection Great Observatory. These include the temperature distribution of the looptop and above-the-looptop hard X-ray coronal sources, the association of coronal X-ray sources with Coronal Mass Ejections, flare loops decreasing in altitude early in the flare impulsive phase, coronal sources moving along a flare loop down to the footpoints and then moving back up to the looptop, and the formation of a cusp structure and new magnetic loops during a loop-loop interaction flare. The impact of these new observations on the standard reconnection flare model will be discussed. This work was supported in part by NASA SEC Guest Investigator Grant 370-16-20-16 and by the RHESSI project.