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Magnetic Flux Ropes in the Solar Photosphere: The Vector Magnetic Field under Active Region Filaments B.W.Lites the Astrophysical Journal, 622:1275-1291,2005, April1. 雑誌会 速報 2005 年 10 月 3 日 J. Kiyohara. Introduction & Abstract.
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Magnetic Flux Ropes in the Solar Photosphere:The Vector Magnetic Field under Active Region FilamentsB.W.Litesthe Astrophysical Journal, 622:1275-1291,2005, April1 雑誌会 速報2005年10月3日 J. Kiyohara
Introduction & Abstract Where is the helicity of solar atmospheric structures generated ? by sheering flows ( Pneuman1983, van Ballegooijen & Martens 1989 etc. ) by actions in the solar interior
Active Region Filaments :An Observational Diagnostic of Twisted Magnetic Fields In quiet regions • - Most prominences reside at • heights well above the photosphere. • In the photosphere, strong magnetic fields • are highly buoyant, and this buoyant • force tends to align them with gravity. • ( Martinez Pillet et al, 1997, • Parker 1979, pp136-151 )
Active Region Filaments :An Observational Diagnostic of Twisted Magnetic Fields In active regions - Arch Filaments upward velocity at the apex of the arch downwards at the two ends of the arch roots on opposite sides of the polarity inversion line(PIL) - very narrow , low-lying filaments follow along the PIL This paper focus on filaments in active region plage well separated from sunspots. • the telltale signature of a flux rope • as measured in the vector magnetic field • The concave geometry is a characteristic signature • for a flux rope whose axis has emerged into the • atmosphere.
3. Observational Requirements -- vector magnetic field measurements DLSP ( Sankarasubramanian et al. 2004 ) SOLIS ( Keller et al. 2003 ) POLIS ( Schmidt et al . 2003 ) TIP and LPSP ( Martinez Pillet et al. 1999 ) -- high angular resolution 1”-2” resolution to reveal concave geometry -- chromospheric diagnostic Ha Stokes spectra and slit-jaw images of the line core
CASE1: An evolving region with persistent concave field geometry NOAA 8948
CASE1: An evolving region with persistent concave field geometry NOAA 8948 White lines : separator between positive and negative polarity magnetic fields (the PIL). Yellow lines : spatially smoothed PIL. In the vicinity of the PIL, Field strengths are generally weaker (400-700G) and fill factors are larger than in the plage on either side ( 1000-1500G ). April 6-10 : the photospheric field is generally aligned with the PIL. April 6-9 : the concave geometry
CASE1: An evolving region with persistent concave field geometry NOAA 8948 April 7 White lines : separator between positive and negative polarity magnetic fields (the PIL). Yellow lines : spatially smoothed PIL. In the vicinity of the PIL, Field strengths are generally weaker (400-700G) and fill factors are larger than in the plage on either side ( 1000-1500G ). April 6-10 : the photospheric field is generally aligned with the PIL. April 6-9 : the concave geometry
Orientation of the horizontal component of the magnetic field vector relative to the local tangent of the PIL. convex geometry ( frel<0 ) concave-up geometry ( 0 < frel< 180deg. )
Discussion ・ The observation presented herein show a qualitatively different vector magnetic field structure at the PIL than is normally found in plage. The magnetic system associated with low-lying filaments has a profound influence on the magnetic field at the photosphere. The likely scenario is that the flux ropes are generated in the solar interior and buoyantly rise through the photophere into the corona. ・ This first study points to the need for more complete studies that will be facilitated by new instrumentation for observing solar vector magnetic fields. not only the imaging of the chromophere and corona but also the velocity field in the photosphere and in the chromosphere, both for Doppler measurements and proper motions.