INFRARED LINES AS PROBES OF SOLAR MAGNETIC FEATURES .7. ON THE NATUREOF THE EVERSHED EFFECT IN SUNSPOTS

Stokes I and V profiles of 1.56mum lines are observed in sunspots and their surroundings near the solar limb. An analysis of these observati ons confirms that the magnetic field of the sunspots continues beyond their visible boundaries in the form of an extensive, low-lying (super penumbral) canopy. We also and that the V profiles, which are only for med above the canopy base, exhibit the Evershed effect with line shift s of 0.5-2 km s-1, while the non-magnetic material below the canopy is at rest. The deduced geometry of the flow outside the sunspot suggest s a resolution of the long standing dispute about the existence or not of an Evershed flow outside the visible sunspot. In addition, the low density of the gas above the canopy base implies that the mass flux i n the magnetic canopy is much smaller (almost-equal-to 10%) than the m ass flux in the penumbra, where the 1.5 mum lines exhibit wavelength s hifts of approximately 4 km s-1. The present observations cast doubt o n the standard interpretation of the photospheric Evershed effect in t erms of a steady flow, in particular if it is driven by the siphon-flo w mechanism.