Magnetic helicity in emerging solar active regions

Journal Article · Thu Apr 10 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/785/1/13· OSTI ID:22357182

Liu, Y.; Hoeksema, J. T.; Bobra, M.; Hayashi, K.; Sun, X. ^[1]; Schuck, P. W. ^[2]

---

1. W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States)
2. Space Weather Laboratory, Code 674, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

Using vector magnetic field data from the Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory, we study magnetic helicity injection into the corona in emerging active regions (ARs) and examine the hemispheric helicity rule. In every region studied, photospheric shearing motion contributes most of the helicity accumulated in the corona. In a sample of 28 emerging ARs, 17 follow the hemisphere rule (61% ± 18% at a 95% confidence interval). Magnetic helicity and twist in 25 ARs (89% ± 11%) have the same sign. The maximum magnetic twist, which depends on the size of an AR, is inferred in a sample of 23 emerging ARs with a bipolar magnetic field configuration.

• OSTI ID: 22357182
• Journal Information: Astrophysical Journal, Vol. 785, 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
HELICITY
INJECTION
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
PHOTOSPHERE
SUN
SUNSPOTS