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

Where is the helicity of solar atmospheric structures generated ? by sheering flows ( Pneuman1983, van Ballegooijen & Martens 1989 etc. ) by actions in the solar interior

In quiet regions

Active Region Filaments : 　　　 An Observational Diagnostic of Twisted Magnetic Fields

- 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 )

In active regions

Active Region Filaments : 　　　 An Observational Diagnostic of Twisted Magnetic Fields

- 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 geometryNOAA 8948

CASE1: An evolving region with persistent concave field geometryNOAA 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 factorsare larger than in the plage on eitherside ( 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 geometryNOAA 8948

April 7White 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 factorsare larger than in the plage on eitherside ( 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 (<0 )

concave-up geometry ( 0 << 180deg. )

CASE2: An active filament in NOAA390

CASE2: An active filament in NOAA390

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.