Vertical mass flux in a sunspot penumbra

We present the first direct measurement of vertical motion in the deepest a tmospheric layers of a penumbra, obtained at hitherto unreached spatial res olution. Isolated hot upflows in the inner penumbra feed the horizontal Eve rshed flow that is observed in the mid and outer penumbra. We discover cool downflows which surround the hot upflows in the inner penumbra. At the out er edge of the penumbra, the Evershed flow terminates in a ring of downflow channels. The upflows transport a sufficient amount of energy to account f or the observed brightness of the penumbra. These measurements have therefo re significant implications for understanding the mass balance and the ener gy transport in a sunspot penumbra.