Dip-like magnetic structure seen in solar prominences

Solar prominences are relatively dense objects suspended in the hot and tenuous solar corona. It has long been speculated that prominence material is supported against gravity by the Lorentz force exerted by magnetic field whose line of force is locally concave upward forming a so-called 'dip'. However, there has been no clear supporting observation mainly due to difficulty in determining 3D magnetic fields within prominences. We present a high-resolution Hα observation of a prominence in which time series of the filtergrams along with Dopplergrams reveals an oscillatory motion of the cool material along a concave upward magnetic dip structure across the main body of the prominence. The observed magnetic dip is an important clue to our understanding of the physics of solar prominences.