W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94035-4085
Limb flares observed in the solar limb are extremely rare, but SDO/HMI’s continuous observations of the Sun are changing that. A few limb flares have been observed in the HMI’s FeI 6173Å, resulting in few interesting publications that studied different aspects of the white-light flares. For example, Martínez Oliveros et al. compared the WL brightening sources with those observed in extreme ultraviolet (EUV) and soft X-ray, Saint-Hilaire et al. analyzed the linear polarization observed in the WL flare loops, Heinzel et al. studied emission mechanisms of the WL off the solar limb, and Zhao et al. reported the quasi-periodic brightening in the off-limb post-flare arcade.
Figure 1| (A) White flare right on the Sun’s east limb; (B) Materials were observed ejected from the Sun; (C) Materials falling back and hanging there for a few minutes; (D) Post-flare arcade formed near the limb.
On 2022 May 3, SDO/HMI captured another limb flare, which was also associated with a filament eruption. The X1.1-class flare, SOL2022-05-03, started on 13:09UT. From the near-limb and off-limb movies below, one can see that the off-limb brightening occurred a few minutes after the onset of the flare right on the limb. Materials are clearly seen ejected from the Sun, but a large fraction of the ejected mass fell back. The falling back materials seemed to reach a balance high above the photosphere, and remained in that position until became invisible in the HMI’s continuum images. Interestingly, a post-flare arcade, although weak in intensity and low in altitude, appeared off the limb above the flaring location.
This event is a case of failed, or partially failed, filament eruption that was captured in white light. We look forward to seeing interesting science that will be done from this event.
 Martínez Oliveros J.-C., Krucker S., Hudson H. S. et al. 2014, ApJL, 780, L28
 Saint-Hilaire P., Schou J., Martínez Oliveros J.-C. et al. 2014, ApJL, 786, L19
 Heinzel P., Kleint L., Kašparová J. & Krucker S. 2017, ApJ, 847, 48
 Zhao, J., Liu, W., & Vial, J.-C., 2021 ApJL, 921, L26