Convection and the Origin of Evershed Flows in Sunspot Penumbrae
نویسندگان
چکیده
منابع مشابه
Convection and the Origin of Evershed Flows in Sunspot Penumbrae
We discuss a numerical 3D radiation-MHD simulation of penumbral fine structure in a small sunspot. This simulation shows the development of short filamentary structures with horizontal flows, similar to observed Evershed flows, and an inward propagation of these structures at a speed compatible with observations. Although the lengths of these filaments are much shorter than observed, we conject...
متن کاملConvection and the Origin of Evershed Flows
Numerical simulations have by now revealed that the fine scale structure of the penumbra in general and the Evershed effect in particular is due to overturning convection, mainly confined to gaps with strongly reduced magnetic field strength. The Evershed flow is the radial component of the overturning convective flow visible at the surface. It is directed outwards – away from the umbra – becau...
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Whereas penumbral models during the last 15 years have been successful in explaining Evershed flows and magnetic field inclination variations in terms of flux tubes, the lack of contact between these models and a convective process needed to explain the penumbral radiative heat flux has been disturbing. We report on recent observational and theoretical evidence that challenge flux tube interpre...
متن کاملA Curious History of Sunspot Penumbrae
Daily records of sunspot group areas compiled by the Royal Observatory, Greenwich, from May of 1874 through 1976 indicate a curious history for the penumbral areas of the smaller sunspot groups. On average, the ratio of penumbral area to umbral area in a sunspot group increases from 5 to 6 as the total sunspot group area increases from 100 to 2000 μHem (a μHem is 10−6 the area of a solar hemisp...
متن کاملHeat transfer in sunspot penumbrae Origin of dark-cored penumbral filaments
Context. Observations at 0. 1 have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims. We investigate the origin of dark cores in penumbral filaments and the surplus brightness of the penumbra using an uncombed penumbral model...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2008
ISSN: 0004-637X,1538-4357
DOI: 10.1086/587982