Small-scale flow field in a sunspot penumbra
نویسنده
چکیده
We have measured velocity maps of a round sunspot near the center of the solar disk. We derive the small-scale velocity field of the penumbra in the deep photosphere. Superimposed on a radial outflow, we find up– and downflows, which are associated with bright and dark features: The flow in the dark component of the penumbra has a larger inclination angle with respect to the surface normal than the bright component, everywhere in the penumbra. The maximum inclination difference is 8◦. In the inner and mid penumbra, bright features (penumbral grains) are associated with an upflow of about 0.6 km s−1. At the outer spot boundary, the flow is inclined downwards predominantly in the dark component (−7◦).
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