Bart De Pontieu

Abstract Solar and stellar flares often exhibit oscillations, or quasi-periodic pulsations (QPPs), across the electromagnetic spectrum. While magnetic-field reconnection drives these events, it remains to be determined whether oscillatory reconnection causes the quasi-periodicity, or whether waves drive or mediate this process.

Abstract The question of what heats the outer solar atmosphere remains one of the longstanding mysteries in astrophysics. Statistical studies of Sun-like stars reveal a correlation between global chromospheric and coronal emissions, constraining theoretical models of potential heating mechanisms. However, spatially resolved observations of the Sun have surprisingly failed to show a similar correlation on small spatial scales.

On May 9, 2016, a NASA solar telescope called the Interface Region Imaging Spectrograph, or IRIS, observed Mercury crossing in front of the sun -- an astronomical phenomenon known as a Mercury transit. During the transit, IRIS focused on Mercury in order to help calibrate its telescope. By observing the planet -- a region that ideally should appear completely dark -- the team could determine just how the optics focus incoming light.