Vector magnetic field measurements along a cooled stereo-imaged coronal loop

Journal Article · Sat Dec 10 00:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/833/1/5· OSTI ID:22868400

Schad, T. A. ^[1]; Penn, M. J. ^[2]; Lin, H. ^[3]

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1. National Solar Observatory, 8 Kiopa‘a Street, Pukalani, HI 96768 (United States)
2. National Solar Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States)
3. Institute for Astronomy, University of Hawai‘i, Pukalani, HI 96768 (United States)

The variation of the vector magnetic field along structures in the solar corona remains unmeasured. Using a unique combination of spectropolarimetry and stereoscopy, we infer and compare the vector magnetic field structure and three-dimensional morphology of an individuated coronal loop structure undergoing a thermal instability. We analyze spectropolarimetric data of the He i λ10830 triplet (1s2s{sup 3}S{sub 1}−1s2p{sup 3}P{sub 2,1,0}) obtained at the Dunn Solar Telescope with the Facility Infrared Spectropolarimeter on 2011 September 19. Cool coronal loops are identified by their prominent drainage signatures in the He i data (redshifts up to 185 km s{sup −1}). Extinction of EUV background radiation along these loops is observed by both the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Extreme Ultraviolet Imager on board spacecraft A of the Solar Terrestrial Relations Observatory, and is used to stereoscopically triangulate the loop geometry up to heights of 70 Mm (0.1R {sub Sun}) above the solar surface. The He i polarized spectra along this loop exhibit signatures indicative of atomic-level polarization, as well as magnetic signatures through the Hanle and Zeeman effects. Spectropolarimetric inversions indicate that the magnetic field is generally oriented along the coronal loop axis, and provide the height dependence of the magnetic field intensity. The technique we demonstrate is a powerful one that may help better understand the thermodynamics of coronal fine-structure magnetism.

• OSTI ID: 22868400
• Journal Information: Astrophysical Journal, Vol. 833, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BACKGROUND RADIATION
CHROMOSPHERE
COMPARATIVE EVALUATIONS
EXTREME ULTRAVIOLET RADIATION
FINE STRUCTURE
INSTABILITY
MAGNETIC FIELDS
MAGNETISM
POLARIZATION
RED SHIFT
SOLAR CORONA
SPACE VEHICLES
SPECTRA
SUN
SUNSPOTS
SURFACES
TELESCOPES
THERMODYNAMICS
THREE-DIMENSIONAL CALCULATIONS
ZEEMAN EFFECT